Files
mp-units/HEAD/users_guide/use_cases/wide_compatibility/index.html
T

2544 lines
70 KiB
HTML

<!doctype html>
<html lang="en" class="no-js">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1">
<meta name="description" content="The quantities and units library for C++">
<meta name="author" content="mp-units Team">
<link rel="canonical" href="https://mpusz.github.io/mp-units/HEAD/users_guide/use_cases/wide_compatibility/">
<link rel="prev" href="../extending_the_library/">
<link rel="next" href="../../examples/tags_index/">
<link rel="alternate" type="application/rss+xml" title="RSS feed" href="../../../feed_rss_created.xml">
<link rel="alternate" type="application/rss+xml" title="RSS feed of updated content" href="../../../feed_rss_updated.xml">
<link rel="icon" href="../../../assets/images/mp-units-color.svg">
<meta name="generator" content="mkdocs-1.6.1, mkdocs-material-9.5.44">
<title>Wide Compatibility - mp-units</title>
<link rel="stylesheet" href="../../../assets/stylesheets/main.0253249f.min.css">
<link rel="stylesheet" href="../../../assets/stylesheets/palette.06af60db.min.css">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CRoboto+Mono:400,400i,700,700i&display=fallback">
<style>:root{--md-text-font:"Roboto";--md-code-font:"Roboto Mono"}</style>
<link rel="stylesheet" href="../../../stylesheets/extra.css">
<script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script>
<meta property="og:type" content="website" >
<meta property="og:title" content="Wide Compatibility - mp-units" >
<meta property="og:description" content="The quantities and units library for C++" >
<meta property="og:image" content="https://mpusz.github.io/mp-units/HEAD/assets/images/social/users_guide/use_cases/wide_compatibility.png" >
<meta property="og:image:type" content="image/png" >
<meta property="og:image:width" content="1200" >
<meta property="og:image:height" content="630" >
<meta property="og:url" content="https://mpusz.github.io/mp-units/HEAD/users_guide/use_cases/wide_compatibility/" >
<meta name="twitter:card" content="summary_large_image" >
<meta name="twitter:title" content="Wide Compatibility - mp-units" >
<meta name="twitter:description" content="The quantities and units library for C++" >
<meta name="twitter:image" content="https://mpusz.github.io/mp-units/HEAD/assets/images/social/users_guide/use_cases/wide_compatibility.png" >
</head>
<body dir="ltr" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo">
<input class="md-toggle" data-md-toggle="drawer" type="checkbox" id="__drawer" autocomplete="off">
<input class="md-toggle" data-md-toggle="search" type="checkbox" id="__search" autocomplete="off">
<label class="md-overlay" for="__drawer"></label>
<div data-md-component="skip">
<a href="#wide-compatibility" class="md-skip">
Skip to content
</a>
</div>
<div data-md-component="announce">
</div>
<div data-md-color-scheme="default" data-md-component="outdated" hidden>
<aside class="md-banner md-banner--warning">
<div class="md-banner__inner md-grid md-typeset">
You're not viewing the latest version.
<a href="../../../..">
<strong>Click here to go to latest.</strong>
</a>
</div>
<script>var el=document.querySelector("[data-md-component=outdated]"),outdated=__md_get("__outdated",sessionStorage);!0===outdated&&el&&(el.hidden=!1)</script>
</aside>
</div>
<header class="md-header" data-md-component="header">
<nav class="md-header__inner md-grid" aria-label="Header">
<a href="../../.." title="mp-units" class="md-header__button md-logo" aria-label="mp-units" data-md-component="logo">
<img src="../../../assets/images/mp-units-transparent-white.svg" alt="logo">
</a>
<label class="md-header__button md-icon" for="__drawer">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg>
</label>
<div class="md-header__title" data-md-component="header-title">
<div class="md-header__ellipsis">
<div class="md-header__topic">
<span class="md-ellipsis">
mp-units
</span>
</div>
<div class="md-header__topic" data-md-component="header-topic">
<span class="md-ellipsis">
Wide Compatibility
</span>
</div>
</div>
</div>
<form class="md-header__option" data-md-component="palette">
<input class="md-option" data-md-color-media="(prefers-color-scheme)" data-md-color-scheme="default" data-md-color-primary="indigo" data-md-color-accent="indigo" aria-label="Switch to light mode" type="radio" name="__palette" id="__palette_0">
<label class="md-header__button md-icon" title="Switch to light mode" for="__palette_1" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M3.9 12c0-1.71 1.39-3.1 3.1-3.1h4V7H7a5 5 0 0 0-5 5 5 5 0 0 0 5 5h4v-1.9H7c-1.71 0-3.1-1.39-3.1-3.1M8 13h8v-2H8zm9-6h-4v1.9h4c1.71 0 3.1 1.39 3.1 3.1s-1.39 3.1-3.1 3.1h-4V17h4a5 5 0 0 0 5-5 5 5 0 0 0-5-5"/></svg>
</label>
<input class="md-option" data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme="default" data-md-color-primary="custom" data-md-color-accent="custom" aria-label="Switch to dark mode" type="radio" name="__palette" id="__palette_1">
<label class="md-header__button md-icon" title="Switch to dark mode" for="__palette_2" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 7a5 5 0 0 1 5 5 5 5 0 0 1-5 5 5 5 0 0 1-5-5 5 5 0 0 1 5-5m0 2a3 3 0 0 0-3 3 3 3 0 0 0 3 3 3 3 0 0 0 3-3 3 3 0 0 0-3-3m0-7 2.39 3.42C13.65 5.15 12.84 5 12 5s-1.65.15-2.39.42zM3.34 7l4.16-.35A7.2 7.2 0 0 0 5.94 8.5c-.44.74-.69 1.5-.83 2.29zm.02 10 1.76-3.77a7.131 7.131 0 0 0 2.38 4.14zM20.65 7l-1.77 3.79a7.02 7.02 0 0 0-2.38-4.15zm-.01 10-4.14.36c.59-.51 1.12-1.14 1.54-1.86.42-.73.69-1.5.83-2.29zM12 22l-2.41-3.44c.74.27 1.55.44 2.41.44.82 0 1.63-.17 2.37-.44z"/></svg>
</label>
<input class="md-option" data-md-color-media="(prefers-color-scheme: dark)" data-md-color-scheme="slate" data-md-color-primary="black" data-md-color-accent="custom" aria-label="Switch to system preference" type="radio" name="__palette" id="__palette_2">
<label class="md-header__button md-icon" title="Switch to system preference" for="__palette_0" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="m17.75 4.09-2.53 1.94.91 3.06-2.63-1.81-2.63 1.81.91-3.06-2.53-1.94L12.44 4l1.06-3 1.06 3zm3.5 6.91-1.64 1.25.59 1.98-1.7-1.17-1.7 1.17.59-1.98L15.75 11l2.06-.05L18.5 9l.69 1.95zm-2.28 4.95c.83-.08 1.72 1.1 1.19 1.85-.32.45-.66.87-1.08 1.27C15.17 23 8.84 23 4.94 19.07c-3.91-3.9-3.91-10.24 0-14.14.4-.4.82-.76 1.27-1.08.75-.53 1.93.36 1.85 1.19-.27 2.86.69 5.83 2.89 8.02a9.96 9.96 0 0 0 8.02 2.89m-1.64 2.02a12.08 12.08 0 0 1-7.8-3.47c-2.17-2.19-3.33-5-3.49-7.82-2.81 3.14-2.7 7.96.31 10.98 3.02 3.01 7.84 3.12 10.98.31"/></svg>
</label>
</form>
<script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(prefers-color-scheme: light)"),input=document.querySelector(media.matches?"[data-md-color-media='(prefers-color-scheme: light)']":"[data-md-color-media='(prefers-color-scheme: dark)']");palette.color.media=input.getAttribute("data-md-color-media"),palette.color.scheme=input.getAttribute("data-md-color-scheme"),palette.color.primary=input.getAttribute("data-md-color-primary"),palette.color.accent=input.getAttribute("data-md-color-accent")}for(var[key,value]of Object.entries(palette.color))document.body.setAttribute("data-md-color-"+key,value)}</script>
<label class="md-header__button md-icon" for="__search">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5"/></svg>
</label>
<div class="md-search" data-md-component="search" role="dialog">
<label class="md-search__overlay" for="__search"></label>
<div class="md-search__inner" role="search">
<form class="md-search__form" name="search">
<input type="text" class="md-search__input" name="query" aria-label="Search" placeholder="Search" autocapitalize="off" autocorrect="off" autocomplete="off" spellcheck="false" data-md-component="search-query" required>
<label class="md-search__icon md-icon" for="__search">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M9.5 3A6.5 6.5 0 0 1 16 9.5c0 1.61-.59 3.09-1.56 4.23l.27.27h.79l5 5-1.5 1.5-5-5v-.79l-.27-.27A6.52 6.52 0 0 1 9.5 16 6.5 6.5 0 0 1 3 9.5 6.5 6.5 0 0 1 9.5 3m0 2C7 5 5 7 5 9.5S7 14 9.5 14 14 12 14 9.5 12 5 9.5 5"/></svg>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11z"/></svg>
</label>
<nav class="md-search__options" aria-label="Search">
<a href="javascript:void(0)" class="md-search__icon md-icon" title="Share" aria-label="Share" data-clipboard data-clipboard-text="" data-md-component="search-share" tabindex="-1">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M18 16.08c-.76 0-1.44.3-1.96.77L8.91 12.7c.05-.23.09-.46.09-.7s-.04-.47-.09-.7l7.05-4.11c.54.5 1.25.81 2.04.81a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3c0 .24.04.47.09.7L8.04 9.81C7.5 9.31 6.79 9 6 9a3 3 0 0 0-3 3 3 3 0 0 0 3 3c.79 0 1.5-.31 2.04-.81l7.12 4.15c-.05.21-.08.43-.08.66 0 1.61 1.31 2.91 2.92 2.91s2.92-1.3 2.92-2.91A2.92 2.92 0 0 0 18 16.08"/></svg>
</a>
<button type="reset" class="md-search__icon md-icon" title="Clear" aria-label="Clear" tabindex="-1">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M19 6.41 17.59 5 12 10.59 6.41 5 5 6.41 10.59 12 5 17.59 6.41 19 12 13.41 17.59 19 19 17.59 13.41 12z"/></svg>
</button>
</nav>
<div class="md-search__suggest" data-md-component="search-suggest"></div>
</form>
<div class="md-search__output">
<div class="md-search__scrollwrap" tabindex="0" data-md-scrollfix>
<div class="md-search-result" data-md-component="search-result">
<div class="md-search-result__meta">
Initializing search
</div>
<ol class="md-search-result__list" role="presentation"></ol>
</div>
</div>
</div>
</div>
</div>
<div class="md-header__source">
<a href="https://github.com/mpusz/mp-units" title="Go to repository" class="md-source" data-md-component="source">
<div class="md-source__icon md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81"/></svg>
</div>
<div class="md-source__repository">
mpusz/mp-units
</div>
</a>
</div>
</nav>
</header>
<div class="md-container" data-md-component="container">
<nav class="md-tabs" aria-label="Tabs" data-md-component="tabs">
<div class="md-grid">
<ul class="md-tabs__list">
<li class="md-tabs__item">
<a href="../../.." class="md-tabs__link">
Home
</a>
</li>
<li class="md-tabs__item">
<a href="../../../getting_started/introduction/" class="md-tabs__link">
Getting Started
</a>
</li>
<li class="md-tabs__item md-tabs__item--active">
<a href="../../terms_and_definitions/" class="md-tabs__link">
User's Guide
</a>
</li>
<li class="md-tabs__item">
<a href="../../../api_reference/" class="md-tabs__link">
API Reference
</a>
</li>
<li class="md-tabs__item">
<a href="../../../blog/" class="md-tabs__link">
Blog
</a>
</li>
<li class="md-tabs__item">
<a href="../../../release_notes/" class="md-tabs__link">
Release Notes
</a>
</li>
</ul>
</div>
</nav>
<main class="md-main" data-md-component="main">
<div class="md-main__inner md-grid">
<div class="md-sidebar md-sidebar--primary" data-md-component="sidebar" data-md-type="navigation" >
<div class="md-sidebar__scrollwrap">
<div class="md-sidebar__inner">
<nav class="md-nav md-nav--primary md-nav--lifted md-nav--integrated" aria-label="Navigation" data-md-level="0">
<label class="md-nav__title" for="__drawer">
<a href="../../.." title="mp-units" class="md-nav__button md-logo" aria-label="mp-units" data-md-component="logo">
<img src="../../../assets/images/mp-units-transparent-white.svg" alt="logo">
</a>
mp-units
</label>
<div class="md-nav__source">
<a href="https://github.com/mpusz/mp-units" title="Go to repository" class="md-source" data-md-component="source">
<div class="md-source__icon md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.6.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2024 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81"/></svg>
</div>
<div class="md-source__repository">
mpusz/mp-units
</div>
</a>
</div>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../.." class="md-nav__link">
<span class="md-ellipsis">
Home
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_2" >
<label class="md-nav__link" for="__nav_2" id="__nav_2_label" tabindex="0">
<span class="md-ellipsis">
Getting Started
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_2">
<span class="md-nav__icon md-icon"></span>
Getting Started
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../../getting_started/introduction/" class="md-nav__link">
<span class="md-ellipsis">
Introduction
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../getting_started/quick_start/" class="md-nav__link">
<span class="md-ellipsis">
Quick Start
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../getting_started/look_and_feel/" class="md-nav__link">
<span class="md-ellipsis">
Look and Feel
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../getting_started/project_structure/" class="md-nav__link">
<span class="md-ellipsis">
Project Structure
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../getting_started/cpp_compiler_support/" class="md-nav__link">
<span class="md-ellipsis">
C++ compiler support (API/ABI)
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../getting_started/installation_and_usage/" class="md-nav__link">
<span class="md-ellipsis">
Installation and Usage
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../getting_started/contributing/" class="md-nav__link">
<span class="md-ellipsis">
Contributing
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../getting_started/faq/" class="md-nav__link">
<span class="md-ellipsis">
FAQ
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--active md-nav__item--section md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3" checked>
<label class="md-nav__link" for="__nav_3" id="__nav_3_label" tabindex="">
<span class="md-ellipsis">
User's Guide
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_3_label" aria-expanded="true">
<label class="md-nav__title" for="__nav_3">
<span class="md-nav__icon md-icon"></span>
User's Guide
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../terms_and_definitions/" class="md-nav__link">
<span class="md-ellipsis">
Terms and Definitions
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3_2" >
<label class="md-nav__link" for="__nav_3_2" id="__nav_3_2_label" tabindex="0">
<span class="md-ellipsis">
Framework Basics
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_3_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_3_2">
<span class="md-nav__icon md-icon"></span>
Framework Basics
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../framework_basics/interface_introduction/" class="md-nav__link">
<span class="md-ellipsis">
Interface Introduction
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/design_overview/" class="md-nav__link">
<span class="md-ellipsis">
Design Overview
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/systems_of_quantities/" class="md-nav__link">
<span class="md-ellipsis">
Systems of Quantities
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/systems_of_units/" class="md-nav__link">
<span class="md-ellipsis">
Systems of Units
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/simple_and_typed_quantities/" class="md-nav__link">
<span class="md-ellipsis">
Simple and Typed Quantities
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/value_conversions/" class="md-nav__link">
<span class="md-ellipsis">
Value Conversions
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/character_of_a_quantity/" class="md-nav__link">
<span class="md-ellipsis">
Character of a Quantity
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/dimensionless_quantities/" class="md-nav__link">
<span class="md-ellipsis">
Dimensionless Quantities
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/quantity_arithmetics/" class="md-nav__link">
<span class="md-ellipsis">
Quantity Arithmetics
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/generic_interfaces/" class="md-nav__link">
<span class="md-ellipsis">
Generic Interfaces
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/faster_than_lightspeed_constants/" class="md-nav__link">
<span class="md-ellipsis">
Faster-than-lightspeed Constants
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/the_affine_space/" class="md-nav__link">
<span class="md-ellipsis">
The Affine Space
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/obtaining_metadata/" class="md-nav__link">
<span class="md-ellipsis">
Obtaining Metadata
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/concepts/" class="md-nav__link">
<span class="md-ellipsis">
Concepts
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../framework_basics/text_output/" class="md-nav__link">
<span class="md-ellipsis">
Text Output
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3_3" >
<label class="md-nav__link" for="__nav_3_3" id="__nav_3_3_label" tabindex="0">
<span class="md-ellipsis">
Systems
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_3_3_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_3_3">
<span class="md-nav__icon md-icon"></span>
Systems
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../systems/introduction/" class="md-nav__link">
<span class="md-ellipsis">
Introduction
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../systems/isq/" class="md-nav__link">
<span class="md-ellipsis">
International System of Quantities (ISQ)
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../systems/si/" class="md-nav__link">
<span class="md-ellipsis">
International System of Units (SI)
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../systems/strong_angular_system/" class="md-nav__link">
<span class="md-ellipsis">
Strong Angular System
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../systems/natural_units/" class="md-nav__link">
<span class="md-ellipsis">
Natural Units
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--active md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3_4" checked>
<label class="md-nav__link" for="__nav_3_4" id="__nav_3_4_label" tabindex="0">
<span class="md-ellipsis">
Use Cases
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_3_4_label" aria-expanded="true">
<label class="md-nav__title" for="__nav_3_4">
<span class="md-nav__icon md-icon"></span>
Use Cases
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../pure_dimensional_analysis/" class="md-nav__link">
<span class="md-ellipsis">
Pure Dimensional Analysis
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../working_with_legacy_interfaces/" class="md-nav__link">
<span class="md-ellipsis">
Working with Legacy Interfaces
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../using_custom_representation_types/" class="md-nav__link">
<span class="md-ellipsis">
Using Custom Representation Types
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../interoperability_with_other_libraries/" class="md-nav__link">
<span class="md-ellipsis">
Interoperability with Other Libraries
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../extending_the_library/" class="md-nav__link">
<span class="md-ellipsis">
Extending the Library
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--active">
<input class="md-nav__toggle md-toggle" type="checkbox" id="__toc">
<label class="md-nav__link md-nav__link--active" for="__toc">
<span class="md-ellipsis">
Wide Compatibility
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<a href="./" class="md-nav__link md-nav__link--active">
<span class="md-ellipsis">
Wide Compatibility
</span>
</a>
<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
<label class="md-nav__title" for="__toc">
<span class="md-nav__icon md-icon"></span>
Table of contents
</label>
<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
<li class="md-nav__item">
<a href="#various-compatibility-options" class="md-nav__link">
<span class="md-ellipsis">
Various compatibility options
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#compatibility-macros" class="md-nav__link">
<span class="md-ellipsis">
Compatibility macros
</span>
</a>
<nav class="md-nav" aria-label="Compatibility macros">
<ul class="md-nav__list">
<li class="md-nav__item">
<a href="#QUANTITY_SPEC" class="md-nav__link">
<span class="md-ellipsis">
QUANTITY_SPEC(name, ...)
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#mp_units_std_fmt" class="md-nav__link">
<span class="md-ellipsis">
MP_UNITS_STD_FMT
</span>
</a>
</li>
<li class="md-nav__item">
<a href="#contracts" class="md-nav__link">
<span class="md-ellipsis">
Contracts
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3_5" >
<label class="md-nav__link" for="__nav_3_5" id="__nav_3_5_label" tabindex="0">
<span class="md-ellipsis">
Examples
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_3_5_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_3_5">
<span class="md-nav__icon md-icon"></span>
Examples
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../examples/tags_index/" class="md-nav__link">
<span class="md-ellipsis">
Tags Index
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3_5_2" >
<label class="md-nav__link" for="__nav_3_5_2" id="__nav_3_5_2_label" tabindex="0">
<span class="md-ellipsis">
All Examples
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="3" aria-labelledby="__nav_3_5_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_3_5_2">
<span class="md-nav__icon md-icon"></span>
All Examples
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../examples/hello_units/" class="md-nav__link">
<span class="md-ellipsis">
hello_units
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../examples/avg_speed/" class="md-nav__link">
<span class="md-ellipsis">
avg_speed
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../examples/si_constants/" class="md-nav__link">
<span class="md-ellipsis">
si_constants
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../examples/hw_voltage/" class="md-nav__link">
<span class="md-ellipsis">
hw_voltage
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_3_6" >
<label class="md-nav__link" for="__nav_3_6" id="__nav_3_6_label" tabindex="0">
<span class="md-ellipsis">
Appendix
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_3_6_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_3_6">
<span class="md-nav__icon md-icon"></span>
Appendix
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../../appendix/glossary/" class="md-nav__link">
<span class="md-ellipsis">
Glossary
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../appendix/references/" class="md-nav__link">
<span class="md-ellipsis">
References
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="../../../api_reference/" class="md-nav__link">
<span class="md-ellipsis">
API Reference
</span>
</a>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_5" >
<div class="md-nav__link md-nav__container">
<a href="../../../blog/" class="md-nav__link ">
<span class="md-ellipsis">
Blog
</span>
</a>
<label class="md-nav__link " for="__nav_5" id="__nav_5_label" tabindex="0">
<span class="md-nav__icon md-icon"></span>
</label>
</div>
<nav class="md-nav" data-md-level="1" aria-labelledby="__nav_5_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_5">
<span class="md-nav__icon md-icon"></span>
Blog
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_5_2" >
<label class="md-nav__link" for="__nav_5_2" id="__nav_5_2_label" tabindex="0">
<span class="md-ellipsis">
Archive
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_5_2_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_5_2">
<span class="md-nav__icon md-icon"></span>
Archive
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../../blog/archive/2024/" class="md-nav__link">
<span class="md-ellipsis">
2024
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../blog/archive/2023/" class="md-nav__link">
<span class="md-ellipsis">
2023
</span>
</a>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item md-nav__item--nested">
<input class="md-nav__toggle md-toggle " type="checkbox" id="__nav_5_3" >
<label class="md-nav__link" for="__nav_5_3" id="__nav_5_3_label" tabindex="0">
<span class="md-ellipsis">
Categories
</span>
<span class="md-nav__icon md-icon"></span>
</label>
<nav class="md-nav" data-md-level="2" aria-labelledby="__nav_5_3_label" aria-expanded="false">
<label class="md-nav__title" for="__nav_5_3">
<span class="md-nav__icon md-icon"></span>
Categories
</label>
<ul class="md-nav__list" data-md-scrollfix>
<li class="md-nav__item">
<a href="../../../blog/category/metrology/" class="md-nav__link">
<span class="md-ellipsis">
Metrology
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../blog/category/releases/" class="md-nav__link">
<span class="md-ellipsis">
Releases
</span>
</a>
</li>
<li class="md-nav__item">
<a href="../../../blog/category/wg21-updates/" class="md-nav__link">
<span class="md-ellipsis">
WG21 Updates
</span>
</a>
</li>
</ul>
</nav>
</li>
</ul>
</nav>
</li>
<li class="md-nav__item">
<a href="../../../release_notes/" class="md-nav__link">
<span class="md-ellipsis">
Release Notes
</span>
</a>
</li>
</ul>
</nav>
</div>
</div>
</div>
<div class="md-content" data-md-component="content">
<article class="md-content__inner md-typeset">
<a href="https://github.com/mpusz/mp-units/edit/master/docs/users_guide/use_cases/wide_compatibility.md" title="Edit this page" class="md-content__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M10 20H6V4h7v5h5v3.1l2-2V8l-6-6H6c-1.1 0-2 .9-2 2v16c0 1.1.9 2 2 2h4zm10.2-7c.1 0 .3.1.4.2l1.3 1.3c.2.2.2.6 0 .8l-1 1-2.1-2.1 1-1c.1-.1.2-.2.4-.2m0 3.9L14.1 23H12v-2.1l6.1-6.1z"/></svg>
</a>
<a href="https://github.com/mpusz/mp-units/raw/master/docs/users_guide/use_cases/wide_compatibility.md" title="View source of this page" class="md-content__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M17 18c.56 0 1 .44 1 1s-.44 1-1 1-1-.44-1-1 .44-1 1-1m0-3c-2.73 0-5.06 1.66-6 4 .94 2.34 3.27 4 6 4s5.06-1.66 6-4c-.94-2.34-3.27-4-6-4m0 6.5a2.5 2.5 0 0 1-2.5-2.5 2.5 2.5 0 0 1 2.5-2.5 2.5 2.5 0 0 1 2.5 2.5 2.5 2.5 0 0 1-2.5 2.5M9.27 20H6V4h7v5h5v4.07c.7.08 1.36.25 2 .49V8l-6-6H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h4.5a8.2 8.2 0 0 1-1.23-2"/></svg>
</a>
<h1 id="wide-compatibility">Wide Compatibility<a class="headerlink" href="#wide-compatibility" title="Permanent link">&para;</a></h1>
<p>The <strong>mp-units</strong> allows us to implement nice and terse code targeting a specific C++ version and
configuration. Such code is easy to write and understand but might not be portable to some older
environments.</p>
<p>However, sometimes, we want to develop code that can be compiled on a wide range of various
compilers and configurations. This is why the library also exposes and uses special preprocessor
macros that can be used to ensure the wide compatibility of our code.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>Those macros are used in our short <a href="../../examples/tags_index/">example applications</a> as those are meant
to be built on all of <a href="../../../getting_started/cpp_compiler_support/">the supported compilers</a>.
Some still do not support <code>std::format</code>, C++ modules, or C++ versions newer than C++20.</p>
</div>
<h2 id="various-compatibility-options">Various compatibility options<a class="headerlink" href="#various-compatibility-options" title="Permanent link">&para;</a></h2>
<p>Depending on your compiler's conformance, you can choose to use any of the below styles to write
your code using <strong>mp-units</strong>:</p>
<div class="tabbed-set tabbed-alternate" data-tabs="1:5"><input checked="checked" id="__tabbed_1_1" name="__tabbed_1" type="radio" /><input id="__tabbed_1_2" name="__tabbed_1" type="radio" /><input id="__tabbed_1_3" name="__tabbed_1" type="radio" /><input id="__tabbed_1_4" name="__tabbed_1" type="radio" /><input id="__tabbed_1_5" name="__tabbed_1" type="radio" /><div class="tabbed-labels"><label for="__tabbed_1_1">C++23</label><label for="__tabbed_1_2">C++20</label><label for="__tabbed_1_3">C++20 with header files</label><label for="__tabbed_1_4">C++20 with header files + libfmt</label><label for="__tabbed_1_5">Wide Compatibility</label></div>
<div class="tabbed-content">
<div class="tabbed-block">
<div class="language-cpp highlight"><pre><span></span><code><span id="__span-0-1"><a id="__codelineno-0-1" name="__codelineno-0-1" href="#__codelineno-0-1"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;format&gt;</span>
</span><span id="__span-0-2"><a id="__codelineno-0-2" name="__codelineno-0-2" href="#__codelineno-0-2"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;iostream&gt;</span>
</span><span id="__span-0-3"><a id="__codelineno-0-3" name="__codelineno-0-3" href="#__codelineno-0-3"></a><span class="k">import</span><span class="w"> </span><span class="n">mp_units</span><span class="p">;</span>
</span><span id="__span-0-4"><a id="__codelineno-0-4" name="__codelineno-0-4" href="#__codelineno-0-4"></a>
</span><span id="__span-0-5"><a id="__codelineno-0-5" name="__codelineno-0-5" href="#__codelineno-0-5"></a><span class="c1">// ...</span>
</span><span id="__span-0-6"><a id="__codelineno-0-6" name="__codelineno-0-6" href="#__codelineno-0-6"></a>
</span><span id="__span-0-7"><a id="__codelineno-0-7" name="__codelineno-0-7" href="#__codelineno-0-7"></a><span class="kr">inline</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">horizontal_length</span><span class="w"> </span><span class="k">final</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">quantity_spec</span><span class="o">&lt;</span><span class="n">isq</span><span class="o">::</span><span class="n">length</span><span class="o">&gt;</span><span class="w"> </span><span class="p">{}</span><span class="w"> </span><span class="n">horizontal_length</span><span class="p">;</span>
</span><span id="__span-0-8"><a id="__codelineno-0-8" name="__codelineno-0-8" href="#__codelineno-0-8"></a>
</span><span id="__span-0-9"><a id="__codelineno-0-9" name="__codelineno-0-9" href="#__codelineno-0-9"></a><span class="c1">// ...</span>
</span><span id="__span-0-10"><a id="__codelineno-0-10" name="__codelineno-0-10" href="#__codelineno-0-10"></a>
</span><span id="__span-0-11"><a id="__codelineno-0-11" name="__codelineno-0-11" href="#__codelineno-0-11"></a><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">format</span><span class="p">(...)</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">;</span>
</span></code></pre></div>
</div>
<div class="tabbed-block">
<div class="language-cpp highlight"><pre><span></span><code><span id="__span-1-1"><a id="__codelineno-1-1" name="__codelineno-1-1" href="#__codelineno-1-1"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;format&gt;</span>
</span><span id="__span-1-2"><a id="__codelineno-1-2" name="__codelineno-1-2" href="#__codelineno-1-2"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;iostream&gt;</span>
</span><span id="__span-1-3"><a id="__codelineno-1-3" name="__codelineno-1-3" href="#__codelineno-1-3"></a><span class="k">import</span><span class="w"> </span><span class="n">mp_units</span><span class="p">;</span>
</span><span id="__span-1-4"><a id="__codelineno-1-4" name="__codelineno-1-4" href="#__codelineno-1-4"></a>
</span><span id="__span-1-5"><a id="__codelineno-1-5" name="__codelineno-1-5" href="#__codelineno-1-5"></a><span class="c1">// ...</span>
</span><span id="__span-1-6"><a id="__codelineno-1-6" name="__codelineno-1-6" href="#__codelineno-1-6"></a>
</span><span id="__span-1-7"><a id="__codelineno-1-7" name="__codelineno-1-7" href="#__codelineno-1-7"></a><span class="kr">inline</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">horizontal_length</span><span class="w"> </span><span class="k">final</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">quantity_spec</span><span class="o">&lt;</span><span class="n">horizontal_length</span><span class="p">,</span><span class="w"> </span><span class="n">isq</span><span class="o">::</span><span class="n">length</span><span class="o">&gt;</span><span class="w"> </span><span class="p">{}</span><span class="w"> </span><span class="n">horizontal_length</span><span class="p">;</span>
</span><span id="__span-1-8"><a id="__codelineno-1-8" name="__codelineno-1-8" href="#__codelineno-1-8"></a>
</span><span id="__span-1-9"><a id="__codelineno-1-9" name="__codelineno-1-9" href="#__codelineno-1-9"></a><span class="c1">// ...</span>
</span><span id="__span-1-10"><a id="__codelineno-1-10" name="__codelineno-1-10" href="#__codelineno-1-10"></a>
</span><span id="__span-1-11"><a id="__codelineno-1-11" name="__codelineno-1-11" href="#__codelineno-1-11"></a><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">format</span><span class="p">(...)</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">;</span>
</span></code></pre></div>
</div>
<div class="tabbed-block">
<div class="language-cpp highlight"><pre><span></span><code><span id="__span-2-1"><a id="__codelineno-2-1" name="__codelineno-2-1" href="#__codelineno-2-1"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/format.h&gt;</span>
</span><span id="__span-2-2"><a id="__codelineno-2-2" name="__codelineno-2-2" href="#__codelineno-2-2"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/ostream.h&gt;</span>
</span><span id="__span-2-3"><a id="__codelineno-2-3" name="__codelineno-2-3" href="#__codelineno-2-3"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/international.h&gt;</span>
</span><span id="__span-2-4"><a id="__codelineno-2-4" name="__codelineno-2-4" href="#__codelineno-2-4"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/isq.h&gt;</span>
</span><span id="__span-2-5"><a id="__codelineno-2-5" name="__codelineno-2-5" href="#__codelineno-2-5"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/si.h&gt;</span>
</span><span id="__span-2-6"><a id="__codelineno-2-6" name="__codelineno-2-6" href="#__codelineno-2-6"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;format&gt;</span>
</span><span id="__span-2-7"><a id="__codelineno-2-7" name="__codelineno-2-7" href="#__codelineno-2-7"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;iostream&gt;</span>
</span><span id="__span-2-8"><a id="__codelineno-2-8" name="__codelineno-2-8" href="#__codelineno-2-8"></a>
</span><span id="__span-2-9"><a id="__codelineno-2-9" name="__codelineno-2-9" href="#__codelineno-2-9"></a><span class="c1">// ...</span>
</span><span id="__span-2-10"><a id="__codelineno-2-10" name="__codelineno-2-10" href="#__codelineno-2-10"></a>
</span><span id="__span-2-11"><a id="__codelineno-2-11" name="__codelineno-2-11" href="#__codelineno-2-11"></a><span class="kr">inline</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">horizontal_length</span><span class="w"> </span><span class="k">final</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">quantity_spec</span><span class="o">&lt;</span><span class="n">horizontal_length</span><span class="p">,</span><span class="w"> </span><span class="n">isq</span><span class="o">::</span><span class="n">length</span><span class="o">&gt;</span><span class="w"> </span><span class="p">{}</span><span class="w"> </span><span class="n">horizontal_length</span><span class="p">;</span>
</span><span id="__span-2-12"><a id="__codelineno-2-12" name="__codelineno-2-12" href="#__codelineno-2-12"></a>
</span><span id="__span-2-13"><a id="__codelineno-2-13" name="__codelineno-2-13" href="#__codelineno-2-13"></a><span class="c1">// ...</span>
</span><span id="__span-2-14"><a id="__codelineno-2-14" name="__codelineno-2-14" href="#__codelineno-2-14"></a>
</span><span id="__span-2-15"><a id="__codelineno-2-15" name="__codelineno-2-15" href="#__codelineno-2-15"></a><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">format</span><span class="p">(...)</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">;</span>
</span></code></pre></div>
</div>
<div class="tabbed-block">
<div class="language-cpp highlight"><pre><span></span><code><span id="__span-3-1"><a id="__codelineno-3-1" name="__codelineno-3-1" href="#__codelineno-3-1"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/format.h&gt;</span>
</span><span id="__span-3-2"><a id="__codelineno-3-2" name="__codelineno-3-2" href="#__codelineno-3-2"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/ostream.h&gt;</span>
</span><span id="__span-3-3"><a id="__codelineno-3-3" name="__codelineno-3-3" href="#__codelineno-3-3"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/international.h&gt;</span>
</span><span id="__span-3-4"><a id="__codelineno-3-4" name="__codelineno-3-4" href="#__codelineno-3-4"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/isq.h&gt;</span>
</span><span id="__span-3-5"><a id="__codelineno-3-5" name="__codelineno-3-5" href="#__codelineno-3-5"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/si.h&gt;</span>
</span><span id="__span-3-6"><a id="__codelineno-3-6" name="__codelineno-3-6" href="#__codelineno-3-6"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;fmt/format.h&gt;</span>
</span><span id="__span-3-7"><a id="__codelineno-3-7" name="__codelineno-3-7" href="#__codelineno-3-7"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;iostream&gt;</span>
</span><span id="__span-3-8"><a id="__codelineno-3-8" name="__codelineno-3-8" href="#__codelineno-3-8"></a>
</span><span id="__span-3-9"><a id="__codelineno-3-9" name="__codelineno-3-9" href="#__codelineno-3-9"></a><span class="c1">// ...</span>
</span><span id="__span-3-10"><a id="__codelineno-3-10" name="__codelineno-3-10" href="#__codelineno-3-10"></a>
</span><span id="__span-3-11"><a id="__codelineno-3-11" name="__codelineno-3-11" href="#__codelineno-3-11"></a><span class="kr">inline</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">horizontal_length</span><span class="w"> </span><span class="k">final</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="n">quantity_spec</span><span class="o">&lt;</span><span class="n">horizontal_length</span><span class="p">,</span><span class="w"> </span><span class="n">isq</span><span class="o">::</span><span class="n">length</span><span class="o">&gt;</span><span class="w"> </span><span class="p">{}</span><span class="w"> </span><span class="n">horizontal_length</span><span class="p">;</span>
</span><span id="__span-3-12"><a id="__codelineno-3-12" name="__codelineno-3-12" href="#__codelineno-3-12"></a>
</span><span id="__span-3-13"><a id="__codelineno-3-13" name="__codelineno-3-13" href="#__codelineno-3-13"></a><span class="c1">// ...</span>
</span><span id="__span-3-14"><a id="__codelineno-3-14" name="__codelineno-3-14" href="#__codelineno-3-14"></a>
</span><span id="__span-3-15"><a id="__codelineno-3-15" name="__codelineno-3-15" href="#__codelineno-3-15"></a><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="n">fmt</span><span class="o">::</span><span class="n">format</span><span class="p">(...)</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">;</span>
</span></code></pre></div>
</div>
<div class="tabbed-block">
<div class="language-cpp highlight"><pre><span></span><code><span id="__span-4-1"><a id="__codelineno-4-1" name="__codelineno-4-1" href="#__codelineno-4-1"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;iostream&gt;</span>
</span><span id="__span-4-2"><a id="__codelineno-4-2" name="__codelineno-4-2" href="#__codelineno-4-2"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/ext/format.h&gt;</span>
</span><span id="__span-4-3"><a id="__codelineno-4-3" name="__codelineno-4-3" href="#__codelineno-4-3"></a><span class="cp">#ifdef MP_UNITS_MODULES</span>
</span><span id="__span-4-4"><a id="__codelineno-4-4" name="__codelineno-4-4" href="#__codelineno-4-4"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/compat_macros.h&gt;</span>
</span><span id="__span-4-5"><a id="__codelineno-4-5" name="__codelineno-4-5" href="#__codelineno-4-5"></a><span class="k">import</span><span class="w"> </span><span class="n">mp_units</span><span class="p">;</span>
</span><span id="__span-4-6"><a id="__codelineno-4-6" name="__codelineno-4-6" href="#__codelineno-4-6"></a><span class="cp">#else</span>
</span><span id="__span-4-7"><a id="__codelineno-4-7" name="__codelineno-4-7" href="#__codelineno-4-7"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/format.h&gt;</span>
</span><span id="__span-4-8"><a id="__codelineno-4-8" name="__codelineno-4-8" href="#__codelineno-4-8"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/ostream.h&gt;</span>
</span><span id="__span-4-9"><a id="__codelineno-4-9" name="__codelineno-4-9" href="#__codelineno-4-9"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/international.h&gt;</span>
</span><span id="__span-4-10"><a id="__codelineno-4-10" name="__codelineno-4-10" href="#__codelineno-4-10"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/isq.h&gt;</span>
</span><span id="__span-4-11"><a id="__codelineno-4-11" name="__codelineno-4-11" href="#__codelineno-4-11"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/systems/si.h&gt;</span>
</span><span id="__span-4-12"><a id="__codelineno-4-12" name="__codelineno-4-12" href="#__codelineno-4-12"></a><span class="cp">#endif</span>
</span><span id="__span-4-13"><a id="__codelineno-4-13" name="__codelineno-4-13" href="#__codelineno-4-13"></a>
</span><span id="__span-4-14"><a id="__codelineno-4-14" name="__codelineno-4-14" href="#__codelineno-4-14"></a><span class="c1">// ...</span>
</span><span id="__span-4-15"><a id="__codelineno-4-15" name="__codelineno-4-15" href="#__codelineno-4-15"></a>
</span><span id="__span-4-16"><a id="__codelineno-4-16" name="__codelineno-4-16" href="#__codelineno-4-16"></a><span class="n">QUANTITY_SPEC</span><span class="p">(</span><span class="n">horizontal_length</span><span class="p">,</span><span class="w"> </span><span class="n">isq</span><span class="o">::</span><span class="n">length</span><span class="p">);</span>
</span><span id="__span-4-17"><a id="__codelineno-4-17" name="__codelineno-4-17" href="#__codelineno-4-17"></a>
</span><span id="__span-4-18"><a id="__codelineno-4-18" name="__codelineno-4-18" href="#__codelineno-4-18"></a><span class="c1">// ...</span>
</span><span id="__span-4-19"><a id="__codelineno-4-19" name="__codelineno-4-19" href="#__codelineno-4-19"></a>
</span><span id="__span-4-20"><a id="__codelineno-4-20" name="__codelineno-4-20" href="#__codelineno-4-20"></a><span class="n">std</span><span class="o">::</span><span class="n">cout</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="n">MP_UNITS_STD_FMT</span><span class="o">::</span><span class="n">format</span><span class="p">(...)</span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">;</span>
</span></code></pre></div>
</div>
</div>
</div>
<div class="admonition tip">
<p class="admonition-title">Tip</p>
<p>Depending on your preferences, you can either write:</p>
<ul>
<li>terse code directly targeting your specific compiler's abilities,</li>
<li>verbose code using preprocessor branches and macros that provide the widest compatibility
across various compilers.</li>
</ul>
</div>
<h2 id="compatibility-macros">Compatibility macros<a class="headerlink" href="#compatibility-macros" title="Permanent link">&para;</a></h2>
<p>This chapter describes only the most essential tools the <strong>mp-units</strong> users need.
All the compatibility macros can be found in the <em>mp-units/compat_macros.h</em> header file.</p>
<div class="admonition tip">
<p class="admonition-title">Tip</p>
<p>The <em>mp-units/compat_macros.h</em> header file is implicitly included when we use "legacy" headers
in our translation units. However, it has to be explicitly included when we use C++20 modules,
as those do not propagate preprocessor macros.</p>
</div>
<h3 id="QUANTITY_SPEC"><code>QUANTITY_SPEC(name, ...)</code><a class="headerlink" href="#QUANTITY_SPEC" title="Permanent link">&para;</a></h3>
<p>Quantity specification definitions benefit from an
<a href="https://en.cppreference.com/w/cpp/language/member_functions#Explicit_object_parameter">explicit object parameter</a>
added in C++23 to remove the need for <abbr title="Curiously Recurring Template Parameter">CRTP</abbr> idiom, which significantly simplifies the code.</p>
<p>This macro benefits from the new C++23 feature if available. Otherwise, it uses the <abbr title="Curiously Recurring Template Parameter">CRTP</abbr> idiom under
the hood.</p>
<h3 id="mp_units_std_fmt"><code>MP_UNITS_STD_FMT</code><a class="headerlink" href="#mp_units_std_fmt" title="Permanent link">&para;</a></h3>
<p>Some of the supported compilers do not support <a href="https://en.cppreference.com/w/cpp/utility/format/format">std::format</a>
and related tools. Also, despite using a conformant compiler, some projects still choose to
use <a href="https://github.com/fmtlib/fmt">fmtlib</a> as their primary formatting facility (e.g., to benefit
from additional features provided with the library).</p>
<p>This macro resolves to either the <code>std</code> or <code>fmt</code> namespace, depending on the value of
<a href="../../../getting_started/installation_and_usage/#MP_UNITS_API_STD_FORMAT">MP_UNITS_API_STD_FORMAT</a>
CMake option.</p>
<p>To include the header files of the underlying text formatting framework, the following include
should be used:</p>
<div class="language-cpp highlight"><pre><span></span><code><span id="__span-5-1"><a id="__codelineno-5-1" name="__codelineno-5-1" href="#__codelineno-5-1"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/ext/format.h&gt;</span>
</span></code></pre></div>
<h3 id="contracts">Contracts<a class="headerlink" href="#contracts" title="Permanent link">&para;</a></h3>
<p>The mp-units library internally does contract checking by default. It can be disabled with a Conan
or CMake option. However, when enabled, it can use either <a href="https://github.com/gsl-lite/gsl-lite">gsl-lite</a>
or <a href="https://github.com/microsoft/GSL">ms-gsl</a>. To write a code that is independent from the
underlying framework, the following preprocessor macros are exposed:</p>
<ul>
<li><code>MP_UNITS_EXPECTS(expr)</code></li>
<li><code>MP_UNITS_EXPECTS_DEBUG(expr)</code></li>
<li><code>MP_UNITS_ASSERT(expr)</code></li>
<li><code>MP_UNITS_ASSERT_DEBUG(expr)</code></li>
</ul>
<p>Their meaning is consistent with respective <a href="https://github.com/gsl-lite/gsl-lite?tab=readme-ov-file#contract-checking-configuration-macros">gsl-lite</a>.</p>
<p>Also, to include the header files of the underlying framework, the following include should be used:</p>
<div class="language-cpp highlight"><pre><span></span><code><span id="__span-6-1"><a id="__codelineno-6-1" name="__codelineno-6-1" href="#__codelineno-6-1"></a><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;mp-units/ext/contracts.h&gt;</span>
</span></code></pre></div>
</article>
</div>
<script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script>
</div>
<button type="button" class="md-top md-icon" data-md-component="top" hidden>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg>
Back to top
</button>
</main>
<footer class="md-footer">
<nav class="md-footer__inner md-grid" aria-label="Footer" >
<a href="../extending_the_library/" class="md-footer__link md-footer__link--prev" aria-label="Previous: Extending the Library">
<div class="md-footer__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11z"/></svg>
</div>
<div class="md-footer__title">
<span class="md-footer__direction">
Previous
</span>
<div class="md-ellipsis">
Extending the Library
</div>
</div>
</a>
<a href="../../examples/tags_index/" class="md-footer__link md-footer__link--next" aria-label="Next: Tags Index">
<div class="md-footer__title">
<span class="md-footer__direction">
Next
</span>
<div class="md-ellipsis">
Tags Index
</div>
</div>
<div class="md-footer__button md-icon">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M4 11v2h12l-5.5 5.5 1.42 1.42L19.84 12l-7.92-7.92L10.5 5.5 16 11z"/></svg>
</div>
</a>
</nav>
<div class="md-footer-meta md-typeset">
<div class="md-footer-meta__inner md-grid">
<div class="md-copyright">
<div class="md-copyright__highlight">
Copyright &copy; 2018-2023 Mateusz Pusz
</div>
Made with
<a href="https://squidfunk.github.io/mkdocs-material/" target="_blank" rel="noopener">
Material for MkDocs
</a>
</div>
</div>
</div>
</footer>
</div>
<div class="md-dialog" data-md-component="dialog">
<div class="md-dialog__inner md-typeset"></div>
</div>
<script id="__config" type="application/json">{"base": "../../..", "features": ["content.action.edit", "content.action.view", "content.code.annotate", "content.code.copy", "navigation.indexes", "navigation.tabs", "navigation.footer", "navigation.top", "search.highlight", "search.share", "search.suggest", "toc.follow", "toc.integrate"], "search": "../../../assets/javascripts/workers/search.6ce7567c.min.js", "translations": {"clipboard.copied": "Copied to clipboard", "clipboard.copy": "Copy to clipboard", "search.result.more.one": "1 more on this page", "search.result.more.other": "# more on this page", "search.result.none": "No matching documents", "search.result.one": "1 matching document", "search.result.other": "# matching documents", "search.result.placeholder": "Type to start searching", "search.result.term.missing": "Missing", "select.version": "Select version"}, "version": {"provider": "mike"}}</script>
<script src="../../../assets/javascripts/bundle.83f73b43.min.js"></script>
<script src="../../../javascripts/mathjax.js"></script>
<script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
<script src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
</body>
</html>