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Antony Polukhin d2ae7fdbd7 char16_t and char32_t conversions now work on gcc for C locale 
Optimizations for C locale
Performance section of documentation updated

[SVN r74432]
2011-09-17 09:09:27 +00:00

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[library Boost.Lexical_Cast
[quickbook 1.5]
[version 1.0]
[copyright 2000-2005 Kevlin Henney]
[copyright 2006-2010 Alexander Nasonov]
[copyright 2011 Antony Polukhin]
[category String and text processing]
[category Miscellaneous]
[license
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
[@http://www.boost.org/LICENSE_1_0.txt])
]
]
[def __numericcast__ [@boost:libs/numeric/conversion/doc/html/boost_numericconversion/improved_numeric_cast__.html `boost::numeric_cast`]]
[def __proposallong__ [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1973.html Lexical Conversion Library Proposal for TR2, N1973 by Kevlin Henney and Beman Dawes]]
[def __proposalshort__ [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1973.html Lexical Conversion Library Proposal for TR2, N1973]]
[section Motivation]
Sometimes a value must be converted to a literal text form, such as an [c++] `int` represented as a `std::string`, or vice-versa, when a `std::string` is interpreted as an `int`. Such examples are common when converting between data types internal to a program and representation external to a program, such as windows and configuration files.
The standard C and C++ libraries offer a number of facilities for performing such conversions. However, they vary with their ease of use, extensibility, and safety.
For instance, there are a number of limitations with the family of standard C functions typified by `atoi`:
* Conversion is supported in one direction only: from text to internal data type. Converting the other way using the C library requires either the inconvenience and compromised safety of the `sprintf` function, or the loss of portability associated with non-standard functions such as `itoa`.
* The range of types supported is only a subset of the built-in numeric types, namely `int`, `long`, and `double`.
* The range of types cannot be extended in a uniform manner. For instance, conversion from string representation to complex or rational.
The standard C functions typified by `strtol` have the same basic limitations, but offer finer control over the conversion process. However, for the common case such control is often either not required or not used. The `scanf` family of functions offer even greater control, but also lack safety and ease of use.
The standard C++ library offers `stringstream` for the kind of in-core formatting being discussed. It offers a great deal of control over the formatting and conversion of I/O to and from arbitrary types through text. However, for simple conversions direct use of `stringstream` can be either clumsy (with the introduction of extra local variables and the loss of infix-expression convenience) or obscure (where `stringstream` objects are created as temporary objects in an expression). Facets provide a comprehensive concept and facility for controlling textual representation, but their perceived complexity and high entry level requires an extreme degree of involvement for simple conversions, and excludes all but a few programmers.
The `lexical_cast` function template offers a convenient and consistent form for supporting common conversions to and from arbitrary types when they are represented as text. The simplification it offers is in expression-level convenience for such conversions. For more involved conversions, such as where precision or formatting need tighter control than is offered by the default behavior of `lexical_cast`, the conventional `std::stringstream` approach is recommended. Where the conversions are numeric to numeric, __numericcast__ may offer more reasonable behavior than `lexical_cast`.
For a good discussion of the options and issues involved in string-based formatting, including comparison of `stringstream`, `lexical_cast`, and others, see Herb Sutter's article, [@http://www.gotw.ca/publications/mill19.htm The String Formatters of Manor Farm]. Also, take a look at the [link boost_lexical_cast.performance Performance] section.
[endsect]
[section Examples]
The following example treats command line arguments as a sequence of numeric data:
``
int main(int argc, char * argv[])
{
using boost::lexical_cast;
using boost::bad_lexical_cast;
std::vector<short> args;
while(*++argv)
{
try
{
args.push_back(lexical_cast<short>(*argv));
}
catch(bad_lexical_cast &)
{
args.push_back(0);
}
}
...
}
``
The following example uses numeric data in a string expression:
``
void log_message(const std::string &);
void log_errno(int yoko)
{
log_message("Error " + boost::lexical_cast<std::string>(yoko) + ": " + strerror(yoko));
}
``
[endsect]
[section Synopsis]
Library features defined in [@boost:boost/lexical_cast.hpp boost/lexical_cast.hpp]:
``
namespace boost
{
class bad_lexical_cast;
template<typename Target, typename Source>
Target lexical_cast(const Source& arg);
}
``
[section lexical_cast]
``
template<typename Target, typename Source>
Target lexical_cast(const Source& arg);
``
Returns the result of streaming arg into a standard library string-based stream and then out as a Target object. Where Target is either `std::string` or `std::wstring`, stream extraction takes the whole content of the string, including spaces, rather than relying on the default `operator>>` behavior. If the conversion is unsuccessful, a `bad_lexical_cast` exception is thrown.
The requirements on the argument and result types are:
* Source is OutputStreamable, meaning that an `operator<<` is defined that takes a `std::ostream` or `std::wostream` object on the left hand side and an instance of the argument type on the right.
* Target is InputStreamable, meaning that an `operator>>` is defined that takes a `std::istream` or `std::wistream` object on the left hand side and an instance of the result type on the right.
* Target is CopyConstructible [20.1.3].
* Target is DefaultConstructible, meaning that it is possible to default-initialize an object of that type [8.5, 20.1.4].
The character type of the underlying stream is assumed to be char unless either the Source or the Target requires wide-character streaming, in which case the underlying stream uses `wchar_t`. Source types that require wide-character streaming are `wchar_t`, `wchar_t *`, and `std::wstring`. Target types that require wide-character streaming are `wchar_t` and `std::wstring`.
Where a higher degree of control is required over conversions, `std::stringstream` and `std::wstringstream` offer a more appropriate path. Where non-stream-based conversions are required, `lexical_cast` is the wrong tool for the job and is not special-cased for such scenarios.
[endsect]
[section bad_lexical_cast]
``
class bad_lexical_cast : public std::bad_cast
{
public:
... // same member function interface as std::exception
};
``
Exception used to indicate runtime lexical_cast failure.
[endsect]
[endsect]
[section Frequently Asked Questions]
* [*Question:] Why does `lexical_cast<int8_t>("127")` throw `bad_lexical_cast`?
* [*Answer:] The type `int8_t` is a `typedef` to `char` or `signed char`. Lexical conversion to these types is simply reading a byte from source but since the source has more than one byte, the exception is thrown.
Please use other integer types such as `int` or `short int`. If bounds checking is important, you can also
call __numericcast__:
`numeric_cast<int8_t>(lexical_cast<int>("127"));`
[pre
]
* [*Question:] Why does `lexical_cast<unsigned char>("127")` throw `bad_lexical_cast`?
* [*Answer:] Lexical conversion to any char type is simply reading a byte from source. But since the source has more than one byte, the exception is thrown.
Please use other integer types such as `int` or `short int`. If bounds checking is important, you can also
call __numericcast__:
`numeric_cast<unsigned char>(lexical_cast<int>("127"));`
[pre
]
* [*Question:] What does `lexical_cast<std::string>` of an `int8_t` or `uint8_t` not do what I expect?
* [*Answer:] As above, note that int8_t and uint8_t are actually chars and are formatted as such. To avoid
this, cast to an integer type first: `lexical_cast<std::string>(static_cast<int>(n));`
[pre
]
* [*Question:] The implementation always resets the `ios_base::skipws` flag of an underlying stream object.
It breaks my `operator>>` that works only in presence of this flag. Can you remove code that resets the flag?
* [*Answer:] May be in a future version. There is no requirement in
__proposallong__ to reset the flag but
remember that __proposalshort__ is not yet accepted by the committee. By the way, it's a great opportunity to
make your `operator>>` conform to the standard.
Read a good C++ book, study `std::sentry` and [@boost:libs/io/doc/ios_state.html `ios_state_saver`].
[pre
]
* [*Question:] Why `std::cout << boost::lexical_cast<unsigned int>("-1");` does not throw, but outputs 4294967295?
* [*Answer:] `boost::lexical_cast` has the behavior of `std::stringstream`, which uses `num_get` functions of
`std::locale` to convert numbers. If we look at the Programming languages — C++, we'll see, that `num_get` uses
the rules of `scanf` for conversions. And in the C99 standard for unsigned input value minus sign is optional, so
if a negative number is read, no errors will arise and the result will be the two's complement.
[endsect]
[section Changes]
* [*boost 1.48.0 :]
* Added code to work with Inf and NaN on any platform.
* Better performance and less memory usage for conversions to float type (and to double type, if `sizeof(double) < sizeof(long double)`).
* [*boost 1.47.0 :]
* Optimizations for "C" and other locales without number grouping.
* Better performance and less memory usage for unsigned char and signed char conversions.
* Better performance and less memory usage for conversions to arithmetic types.
* Better performance and less memory usage for conversions from arithmetic type to arithmetic type.
* Directly construct Target from Source on some conversions (like conversions from string to string, from char array to string, from char to char and others).
* [*boost 1.34.0 :]
* Better performance for many combinations of Source and Target types. For more details refer to Alexander Nasonovs article [@http://accu.org/index.php/journals/1375 Fine Tuning for lexical_cast, Overload #74, August 2006] [@http://www.accu.org/var/uploads/journals/overload74.pdf (PDF)].
* [*boost 1.33.0 :]
* Call-by-const reference for the parameters. This requires partial specialization of class templates, so it doesn't work for MSVC 6, and it uses the original pass by value there.
* The MSVC 6 support is deprecated, and will be removed in a future Boost version.
* [*Earlier :]
* The previous version of lexical_cast used the default stream precision for reading and writing floating-point numbers. For numerics that have a corresponding specialization of `std::numeric_limits`, the current version now chooses a precision to match.
* The previous version of lexical_cast did not support conversion to or from any wide-character-based types. For compilers with full language and library support for wide characters, `lexical_cast` now supports conversions from `wchar_t`, `wchar_t *`, and `std::wstring` and to `wchar_t` and `std::wstring`.
* The previous version of `lexical_cast` assumed that the conventional stream extractor operators were sufficient for reading values. However, string I/O is asymmetric, with the result that spaces play the role of I/O separators rather than string content. The current version fixes this error for `std::string` and, where supported, `std::wstring`: `lexical_cast<std::string>("Hello, World")` succeeds instead of failing with a `bad_lexical_cast` exception.
* The previous version of `lexical_cast` allowed unsafe and meaningless conversions to pointers. The current version now throws a `bad_lexical_cast` for conversions to pointers: `lexical_cast<char *>("Goodbye, World")` now throws an exception instead of causing undefined behavior.
[endsect]
[section Performance]
In most cases `boost::lexical_cast` is faster than `scanf`, `printf`, `std::stringstream`. For more detailed info you can look at the tables below.
[section Tests description]
All the tests measure execution speed in milliseconds for 10000 iterations of the following code blocks:
[table:legend Tests source code
[[Test name] [Code]]
[[lexical_cast]
[``
_out = boost::lexical_cast<OUTTYPE>(_in);
``]
]
[[std::stringstream with construction]
[``
std::stringstream ss;
ss << _in;
if (ss.fail()) throw std::logic_error(descr);
ss >> _out;
if (ss.fail()) throw std::logic_error(descr);
``]
]
[[std::stringstream without construction]
[``
ss << _in; // ss is an instance of std::stringstream
if (ss.fail()) throw std::logic_error(descr);
ss >> _out;
if (ss.fail()) throw std::logic_error(descr);
/* reseting std::stringstream to use it again */
ss.str(std::string());
ss.clear();
``]
]
[[scanf/printf]
[``
typename OUTTYPE::value_type buffer[500];
sprintf( (char*)buffer, conv, _in);
_out = buffer;
``]
]
]
Fastest results are highlitened with "!!! *x* !!!".
Do not use this results to compare compilers, because tests were taken on different hardware.
[endsect]
[/ BEGIN of section, generated by performance measuring program ]
[section clang-linux-2.8][table:id Performance Table (clang-linux-2.8)
[[From->To] [lexical_cast] [std::stringstream with construction] [std::stringstream without construction][scanf/printf]]
[[ string->char ][ !!! *<1* !!! ][ 148 ][ 14 ][ 12 ]]
[[ string->signed char ][ !!! *<1* !!! ][ 97 ][ 8 ][ 7 ]]
[[ string->unsigned char ][ !!! *<1* !!! ][ 90 ][ 8 ][ 13 ]]
[[ string->int ][ !!! *4* !!! ][ 102 ][ 19 ][ 15 ]]
[[ string->short ][ !!! *4* !!! ][ 105 ][ 20 ][ 15 ]]
[[ string->long int ][ !!! *4* !!! ][ 105 ][ 19 ][ 15 ]]
[[ string->long long ][ !!! *4* !!! ][ 115 ][ 19 ][ 14 ]]
[[ string->unsigned int ][ !!! *4* !!! ][ 102 ][ 18 ][ 14 ]]
[[ string->unsigned short ][ !!! *4* !!! ][ 101 ][ 19 ][ 15 ]]
[[ string->unsigned long int ][ !!! *3* !!! ][ 107 ][ 20 ][ 14 ]]
[[ string->unsigned long long ][ !!! *3* !!! ][ 103 ][ 20 ][ 14 ]]
[[ string->bool ][ !!! *<1* !!! ][ 97 ][ 16 ][ 8 ]]
[[ string->float ][ !!! *21* !!! ][ 170 ][ 61 ][ 32 ]]
[[ string->double ][ !!! *18* !!! ][ 206 ][ 93 ][ 58 ]]
[[ string->long double ][ 135 ][ 221 ][ 94 ][ !!! *57* !!! ]]
[[ char->string ][ !!! *7* !!! ][ 100 ][ 17 ][ 13 ]]
[[ unsigned char->string ][ !!! *7* !!! ][ 99 ][ 18 ][ 16 ]]
[[ signed char->string ][ !!! *7* !!! ][ 101 ][ 17 ][ 12 ]]
[[ int->string ][ !!! *13* !!! ][ 110 ][ 23 ][ 15 ]]
[[ short->string ][ !!! *13* !!! ][ 112 ][ 24 ][ 18 ]]
[[ long int->string ][ !!! *13* !!! ][ 119 ][ 23 ][ 17 ]]
[[ long long->string ][ !!! *13* !!! ][ 110 ][ 23 ][ 18 ]]
[[ unsigned int->string ][ !!! *14* !!! ][ 113 ][ 24 ][ 17 ]]
[[ unsigned short->string ][ !!! *13* !!! ][ 108 ][ 24 ][ 17 ]]
[[ unsigned long int->string ][ !!! *13* !!! ][ 109 ][ 24 ][ 16 ]]
[[ unsigned long long->string ][ !!! *13* !!! ][ 110 ][ 23 ][ 17 ]]
[[ bool->string ][ !!! *7* !!! ][ 105 ][ 24 ][ 12 ]]
[[ float->string ][ 70 ][ 192 ][ 94 ][ !!! *49* !!! ]]
[[ double->string ][ 106 ][ 217 ][ 122 ][ !!! *76* !!! ]]
[[ long double->string ][ 120 ][ 219 ][ 123 ][ !!! *80* !!! ]]
[[ char*->char ][ !!! *2* !!! ][ 90 ][ 9 ][ 8 ]]
[[ char*->signed char ][ !!! *2* !!! ][ 87 ][ 10 ][ 7 ]]
[[ char*->unsigned char ][ !!! *3* !!! ][ 90 ][ 10 ][ 13 ]]
[[ char*->int ][ !!! *6* !!! ][ 107 ][ 21 ][ 15 ]]
[[ char*->short ][ !!! *6* !!! ][ 110 ][ 19 ][ 14 ]]
[[ char*->long int ][ !!! *6* !!! ][ 103 ][ 19 ][ 14 ]]
[[ char*->long long ][ !!! *7* !!! ][ 104 ][ 20 ][ 15 ]]
[[ char*->unsigned int ][ !!! *6* !!! ][ 101 ][ 20 ][ 15 ]]
[[ char*->unsigned short ][ !!! *7* !!! ][ 100 ][ 20 ][ 14 ]]
[[ char*->unsigned long int ][ !!! *6* !!! ][ 105 ][ 22 ][ 15 ]]
[[ char*->unsigned long long ][ !!! *7* !!! ][ 106 ][ 21 ][ 14 ]]
[[ char*->bool ][ !!! *2* !!! ][ 99 ][ 18 ][ 7 ]]
[[ char*->float ][ !!! *22* !!! ][ 159 ][ 67 ][ 33 ]]
[[ char*->double ][ !!! *20* !!! ][ 205 ][ 94 ][ 58 ]]
[[ char*->long double ][ 140 ][ 214 ][ 95 ][ !!! *58* !!! ]]
[[ unsigned char*->char ][ !!! *2* !!! ][ 92 ][ 9 ][ 7 ]]
[[ unsigned char*->signed char ][ !!! *2* !!! ][ 89 ][ 10 ][ 7 ]]
[[ unsigned char*->unsigned char ][ !!! *2* !!! ][ 89 ][ 10 ][ 14 ]]
[[ unsigned char*->int ][ !!! *6* !!! ][ 104 ][ 20 ][ 14 ]]
[[ unsigned char*->short ][ !!! *6* !!! ][ 106 ][ 21 ][ 14 ]]
[[ unsigned char*->long int ][ !!! *6* !!! ][ 105 ][ 19 ][ 14 ]]
[[ unsigned char*->long long ][ !!! *6* !!! ][ 106 ][ 20 ][ 15 ]]
[[ unsigned char*->unsigned int ][ !!! *7* !!! ][ 105 ][ 19 ][ 14 ]]
[[ unsigned char*->unsigned short ][ !!! *6* !!! ][ 103 ][ 19 ][ 14 ]]
[[ unsigned char*->unsigned long int ][ !!! *6* !!! ][ 106 ][ 19 ][ 14 ]]
[[ unsigned char*->unsigned long long ][ !!! *6* !!! ][ 104 ][ 21 ][ 15 ]]
[[ unsigned char*->bool ][ !!! *2* !!! ][ 102 ][ 18 ][ 7 ]]
[[ unsigned char*->float ][ !!! *23* !!! ][ 160 ][ 66 ][ 32 ]]
[[ unsigned char*->double ][ !!! *20* !!! ][ 201 ][ 95 ][ 58 ]]
[[ unsigned char*->long double ][ 144 ][ 221 ][ 95 ][ !!! *60* !!! ]]
[[ unsigned char*->string ][ !!! *12* !!! ][ 104 ][ 23 ][ --- ]]
[[ signed char*->char ][ !!! *2* !!! ][ 90 ][ 9 ][ 7 ]]
[[ signed char*->signed char ][ !!! *2* !!! ][ 89 ][ 9 ][ 7 ]]
[[ signed char*->unsigned char ][ !!! *2* !!! ][ 89 ][ 10 ][ 13 ]]
[[ signed char*->int ][ !!! *6* !!! ][ 106 ][ 19 ][ 15 ]]
[[ signed char*->short ][ !!! *6* !!! ][ 107 ][ 20 ][ 15 ]]
[[ signed char*->long int ][ !!! *6* !!! ][ 103 ][ 19 ][ 14 ]]
[[ signed char*->long long ][ !!! *6* !!! ][ 103 ][ 19 ][ 14 ]]
[[ signed char*->unsigned int ][ !!! *6* !!! ][ 101 ][ 19 ][ 15 ]]
[[ signed char*->unsigned short ][ !!! *6* !!! ][ 101 ][ 19 ][ 16 ]]
[[ signed char*->unsigned long int ][ !!! *6* !!! ][ 105 ][ 22 ][ 15 ]]
[[ signed char*->unsigned long long ][ !!! *6* !!! ][ 104 ][ 21 ][ 15 ]]
[[ signed char*->bool ][ !!! *2* !!! ][ 100 ][ 18 ][ 7 ]]
[[ signed char*->float ][ !!! *23* !!! ][ 161 ][ 62 ][ 32 ]]
[[ signed char*->double ][ !!! *20* !!! ][ 207 ][ 102 ][ 57 ]]
[[ signed char*->long double ][ 144 ][ 216 ][ 96 ][ !!! *63* !!! ]]
[[ signed char*->string ][ !!! *12* !!! ][ 104 ][ 23 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 110 ][ 22 ][ --- ]]
[[ float->double ][ !!! *<1* !!! ][ 223 ][ 113 ][ --- ]]
[[ double->double ][ !!! *<1* !!! ][ 227 ][ 111 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 231 ][ 122 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 229 ][ 121 ][ --- ]]
[[ char->unsigned char ][ !!! *<1* !!! ][ 90 ][ 8 ][ --- ]]
[[ char->signed char ][ !!! *<1* !!! ][ 88 ][ 8 ][ --- ]]
[[ unsigned char->char ][ !!! *<1* !!! ][ 89 ][ 8 ][ --- ]]
[[ signed char->char ][ !!! *<1* !!! ][ 91 ][ 9 ][ --- ]]
]
[endsect]
[section gcc-4.4][table:id Performance Table (gcc-4.4)
[[From->To] [lexical_cast] [std::stringstream with construction] [std::stringstream without construction][scanf/printf]]
[[ string->char ][ !!! *<1* !!! ][ 90 ][ 7 ][ 7 ]]
[[ string->signed char ][ !!! *<1* !!! ][ 88 ][ 7 ][ 8 ]]
[[ string->unsigned char ][ !!! *<1* !!! ][ 88 ][ 8 ][ 14 ]]
[[ string->int ][ !!! *3* !!! ][ 103 ][ 18 ][ 15 ]]
[[ string->short ][ !!! *3* !!! ][ 105 ][ 20 ][ 15 ]]
[[ string->long int ][ !!! *3* !!! ][ 101 ][ 18 ][ 16 ]]
[[ string->long long ][ !!! *3* !!! ][ 101 ][ 18 ][ 15 ]]
[[ string->unsigned int ][ !!! *3* !!! ][ 98 ][ 23 ][ 14 ]]
[[ string->unsigned short ][ !!! *3* !!! ][ 100 ][ 17 ][ 14 ]]
[[ string->unsigned long int ][ !!! *3* !!! ][ 100 ][ 21 ][ 15 ]]
[[ string->unsigned long long ][ !!! *3* !!! ][ 99 ][ 19 ][ 15 ]]
[[ string->bool ][ !!! *<1* !!! ][ 95 ][ 16 ][ 8 ]]
[[ string->float ][ !!! *13* !!! ][ 160 ][ 61 ][ 33 ]]
[[ string->double ][ !!! *14* !!! ][ 206 ][ 93 ][ 59 ]]
[[ string->long double ][ 128 ][ 217 ][ 96 ][ !!! *61* !!! ]]
[[ char->string ][ !!! *7* !!! ][ 100 ][ 17 ][ 12 ]]
[[ unsigned char->string ][ !!! *7* !!! ][ 109 ][ 17 ][ 16 ]]
[[ signed char->string ][ !!! *7* !!! ][ 99 ][ 17 ][ 12 ]]
[[ int->string ][ !!! *13* !!! ][ 110 ][ 21 ][ 15 ]]
[[ short->string ][ !!! *14* !!! ][ 110 ][ 22 ][ 17 ]]
[[ long int->string ][ !!! *14* !!! ][ 109 ][ 21 ][ 16 ]]
[[ long long->string ][ !!! *13* !!! ][ 114 ][ 20 ][ 17 ]]
[[ unsigned int->string ][ !!! *13* !!! ][ 109 ][ 23 ][ 15 ]]
[[ unsigned short->string ][ !!! *14* !!! ][ 109 ][ 23 ][ 17 ]]
[[ unsigned long int->string ][ !!! *13* !!! ][ 112 ][ 23 ][ 16 ]]
[[ unsigned long long->string ][ !!! *14* !!! ][ 109 ][ 21 ][ 17 ]]
[[ bool->string ][ !!! *7* !!! ][ 108 ][ 23 ][ 11 ]]
[[ float->string ][ 63 ][ 185 ][ 92 ][ !!! *50* !!! ]]
[[ double->string ][ 106 ][ 216 ][ 116 ][ !!! *75* !!! ]]
[[ long double->string ][ 118 ][ 219 ][ 119 ][ !!! *80* !!! ]]
[[ char*->char ][ !!! *1* !!! ][ 93 ][ 9 ][ 9 ]]
[[ char*->signed char ][ !!! *1* !!! ][ 92 ][ 9 ][ 9 ]]
[[ char*->unsigned char ][ !!! *1* !!! ][ 92 ][ 9 ][ 14 ]]
[[ char*->int ][ !!! *4* !!! ][ 107 ][ 19 ][ 15 ]]
[[ char*->short ][ !!! *5* !!! ][ 109 ][ 19 ][ 15 ]]
[[ char*->long int ][ !!! *4* !!! ][ 113 ][ 19 ][ 15 ]]
[[ char*->long long ][ !!! *4* !!! ][ 108 ][ 20 ][ 15 ]]
[[ char*->unsigned int ][ !!! *4* !!! ][ 106 ][ 19 ][ 15 ]]
[[ char*->unsigned short ][ !!! *4* !!! ][ 106 ][ 18 ][ 15 ]]
[[ char*->unsigned long int ][ !!! *4* !!! ][ 103 ][ 22 ][ 15 ]]
[[ char*->unsigned long long ][ !!! *4* !!! ][ 105 ][ 20 ][ 15 ]]
[[ char*->bool ][ !!! *1* !!! ][ 104 ][ 18 ][ 8 ]]
[[ char*->float ][ !!! *15* !!! ][ 164 ][ 62 ][ 33 ]]
[[ char*->double ][ !!! *16* !!! ][ 203 ][ 97 ][ 58 ]]
[[ char*->long double ][ 132 ][ 223 ][ 98 ][ !!! *60* !!! ]]
[[ unsigned char*->char ][ !!! *2* !!! ][ 90 ][ 9 ][ 8 ]]
[[ unsigned char*->signed char ][ !!! *2* !!! ][ 92 ][ 10 ][ 8 ]]
[[ unsigned char*->unsigned char ][ !!! *2* !!! ][ 91 ][ 9 ][ 14 ]]
[[ unsigned char*->int ][ !!! *6* !!! ][ 106 ][ 20 ][ 15 ]]
[[ unsigned char*->short ][ !!! *6* !!! ][ 106 ][ 21 ][ 15 ]]
[[ unsigned char*->long int ][ !!! *6* !!! ][ 111 ][ 19 ][ 15 ]]
[[ unsigned char*->long long ][ !!! *6* !!! ][ 107 ][ 20 ][ 15 ]]
[[ unsigned char*->unsigned int ][ !!! *6* !!! ][ 105 ][ 19 ][ 15 ]]
[[ unsigned char*->unsigned short ][ !!! *6* !!! ][ 103 ][ 18 ][ 15 ]]
[[ unsigned char*->unsigned long int ][ !!! *6* !!! ][ 106 ][ 22 ][ 14 ]]
[[ unsigned char*->unsigned long long ][ !!! *6* !!! ][ 105 ][ 20 ][ 14 ]]
[[ unsigned char*->bool ][ !!! *2* !!! ][ 106 ][ 18 ][ 8 ]]
[[ unsigned char*->float ][ !!! *15* !!! ][ 167 ][ 68 ][ 33 ]]
[[ unsigned char*->double ][ !!! *17* !!! ][ 203 ][ 99 ][ 58 ]]
[[ unsigned char*->long double ][ 129 ][ 216 ][ 97 ][ !!! *61* !!! ]]
[[ unsigned char*->string ][ !!! *13* !!! ][ 111 ][ 23 ][ --- ]]
[[ signed char*->char ][ !!! *2* !!! ][ 92 ][ 9 ][ 8 ]]
[[ signed char*->signed char ][ !!! *2* !!! ][ 91 ][ 9 ][ 8 ]]
[[ signed char*->unsigned char ][ !!! *2* !!! ][ 91 ][ 9 ][ 14 ]]
[[ signed char*->int ][ !!! *6* !!! ][ 107 ][ 19 ][ 15 ]]
[[ signed char*->short ][ !!! *6* !!! ][ 109 ][ 24 ][ 14 ]]
[[ signed char*->long int ][ !!! *6* !!! ][ 112 ][ 19 ][ 15 ]]
[[ signed char*->long long ][ !!! *5* !!! ][ 107 ][ 20 ][ 15 ]]
[[ signed char*->unsigned int ][ !!! *6* !!! ][ 108 ][ 20 ][ 15 ]]
[[ signed char*->unsigned short ][ !!! *6* !!! ][ 104 ][ 18 ][ 15 ]]
[[ signed char*->unsigned long int ][ !!! *6* !!! ][ 102 ][ 22 ][ 15 ]]
[[ signed char*->unsigned long long ][ !!! *6* !!! ][ 104 ][ 20 ][ 15 ]]
[[ signed char*->bool ][ !!! *2* !!! ][ 104 ][ 18 ][ 8 ]]
[[ signed char*->float ][ !!! *16* !!! ][ 165 ][ 63 ][ 33 ]]
[[ signed char*->double ][ !!! *16* !!! ][ 203 ][ 98 ][ 59 ]]
[[ signed char*->long double ][ 129 ][ 215 ][ 98 ][ !!! *61* !!! ]]
[[ signed char*->string ][ !!! *13* !!! ][ 109 ][ 21 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 109 ][ 21 ][ --- ]]
[[ float->double ][ !!! *<1* !!! ][ 221 ][ 102 ][ --- ]]
[[ double->double ][ !!! *<1* !!! ][ 223 ][ 103 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 231 ][ 115 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 231 ][ 115 ][ --- ]]
[[ char->unsigned char ][ !!! *<1* !!! ][ 92 ][ 8 ][ --- ]]
[[ char->signed char ][ !!! *<1* !!! ][ 88 ][ 8 ][ --- ]]
[[ unsigned char->char ][ !!! *<1* !!! ][ 88 ][ 7 ][ --- ]]
[[ signed char->char ][ !!! *<1* !!! ][ 89 ][ 8 ][ --- ]]
]
[endsect]
[section gcc-4.5][table:id Performance Table (gcc-4.5)
[[From->To] [lexical_cast] [std::stringstream with construction] [std::stringstream without construction][scanf/printf]]
[[ string->char ][ !!! *<1* !!! ][ 91 ][ 8 ][ 7 ]]
[[ string->signed char ][ !!! *<1* !!! ][ 91 ][ 8 ][ 7 ]]
[[ string->unsigned char ][ !!! *<1* !!! ][ 90 ][ 8 ][ 13 ]]
[[ string->int ][ !!! *3* !!! ][ 100 ][ 20 ][ 14 ]]
[[ string->short ][ !!! *3* !!! ][ 106 ][ 20 ][ 14 ]]
[[ string->long int ][ !!! *3* !!! ][ 100 ][ 18 ][ 14 ]]
[[ string->long long ][ !!! *9* !!! ][ 100 ][ 18 ][ 15 ]]
[[ string->unsigned int ][ !!! *3* !!! ][ 97 ][ 20 ][ 14 ]]
[[ string->unsigned short ][ !!! *3* !!! ][ 102 ][ 17 ][ 14 ]]
[[ string->unsigned long int ][ !!! *3* !!! ][ 97 ][ 21 ][ 14 ]]
[[ string->unsigned long long ][ !!! *3* !!! ][ 97 ][ 19 ][ 14 ]]
[[ string->bool ][ !!! *<1* !!! ][ 95 ][ 16 ][ 7 ]]
[[ string->float ][ !!! *15* !!! ][ 157 ][ 63 ][ 32 ]]
[[ string->double ][ !!! *17* !!! ][ 203 ][ 95 ][ 59 ]]
[[ string->long double ][ 129 ][ 216 ][ 93 ][ !!! *58* !!! ]]
[[ char->string ][ !!! *8* !!! ][ 100 ][ 17 ][ 10 ]]
[[ unsigned char->string ][ !!! *8* !!! ][ 96 ][ 18 ][ 16 ]]
[[ signed char->string ][ !!! *8* !!! ][ 96 ][ 18 ][ 10 ]]
[[ int->string ][ !!! *14* !!! ][ 105 ][ 22 ][ 15 ]]
[[ short->string ][ !!! *14* !!! ][ 107 ][ 23 ][ 17 ]]
[[ long int->string ][ !!! *14* !!! ][ 109 ][ 22 ][ 17 ]]
[[ long long->string ][ !!! *14* !!! ][ 105 ][ 22 ][ 18 ]]
[[ unsigned int->string ][ !!! *14* !!! ][ 105 ][ 25 ][ 15 ]]
[[ unsigned short->string ][ !!! *15* !!! ][ 105 ][ 23 ][ 17 ]]
[[ unsigned long int->string ][ !!! *14* !!! ][ 109 ][ 24 ][ 17 ]]
[[ unsigned long long->string ][ !!! *14* !!! ][ 102 ][ 23 ][ 17 ]]
[[ bool->string ][ !!! *8* !!! ][ 104 ][ 23 ][ 12 ]]
[[ float->string ][ 66 ][ 181 ][ 92 ][ !!! *49* !!! ]]
[[ double->string ][ 107 ][ 215 ][ 120 ][ !!! *75* !!! ]]
[[ long double->string ][ 117 ][ 221 ][ 125 ][ !!! *79* !!! ]]
[[ char*->char ][ !!! *1* !!! ][ 89 ][ 9 ][ 7 ]]
[[ char*->signed char ][ !!! *1* !!! ][ 90 ][ 9 ][ 7 ]]
[[ char*->unsigned char ][ !!! *2* !!! ][ 90 ][ 9 ][ 13 ]]
[[ char*->int ][ !!! *7* !!! ][ 103 ][ 20 ][ 15 ]]
[[ char*->short ][ !!! *6* !!! ][ 102 ][ 29 ][ 14 ]]
[[ char*->long int ][ !!! *7* !!! ][ 101 ][ 20 ][ 15 ]]
[[ char*->long long ][ !!! *6* !!! ][ 102 ][ 20 ][ 14 ]]
[[ char*->unsigned int ][ !!! *6* !!! ][ 99 ][ 19 ][ 14 ]]
[[ char*->unsigned short ][ !!! *6* !!! ][ 101 ][ 18 ][ 14 ]]
[[ char*->unsigned long int ][ !!! *6* !!! ][ 102 ][ 22 ][ 14 ]]
[[ char*->unsigned long long ][ !!! *6* !!! ][ 101 ][ 21 ][ 14 ]]
[[ char*->bool ][ !!! *3* !!! ][ 98 ][ 18 ][ 7 ]]
[[ char*->float ][ !!! *18* !!! ][ 162 ][ 63 ][ 31 ]]
[[ char*->double ][ !!! *17* !!! ][ 203 ][ 96 ][ 58 ]]
[[ char*->long double ][ 135 ][ 214 ][ 98 ][ !!! *58* !!! ]]
[[ unsigned char*->char ][ !!! *2* !!! ][ 87 ][ 9 ][ 7 ]]
[[ unsigned char*->signed char ][ !!! *2* !!! ][ 87 ][ 9 ][ 7 ]]
[[ unsigned char*->unsigned char ][ !!! *3* !!! ][ 87 ][ 9 ][ 13 ]]
[[ unsigned char*->int ][ !!! *6* !!! ][ 105 ][ 20 ][ 14 ]]
[[ unsigned char*->short ][ !!! *6* !!! ][ 102 ][ 21 ][ 14 ]]
[[ unsigned char*->long int ][ !!! *6* !!! ][ 101 ][ 20 ][ 14 ]]
[[ unsigned char*->long long ][ !!! *6* !!! ][ 102 ][ 20 ][ 14 ]]
[[ unsigned char*->unsigned int ][ !!! *6* !!! ][ 99 ][ 19 ][ 14 ]]
[[ unsigned char*->unsigned short ][ !!! *6* !!! ][ 100 ][ 18 ][ 14 ]]
[[ unsigned char*->unsigned long int ][ !!! *6* !!! ][ 101 ][ 24 ][ 14 ]]
[[ unsigned char*->unsigned long long ][ !!! *6* !!! ][ 100 ][ 20 ][ 14 ]]
[[ unsigned char*->bool ][ !!! *3* !!! ][ 99 ][ 18 ][ 8 ]]
[[ unsigned char*->float ][ !!! *17* !!! ][ 164 ][ 64 ][ 32 ]]
[[ unsigned char*->double ][ !!! *18* !!! ][ 201 ][ 94 ][ 58 ]]
[[ unsigned char*->long double ][ 133 ][ 217 ][ 95 ][ !!! *60* !!! ]]
[[ unsigned char*->string ][ !!! *14* !!! ][ 103 ][ 23 ][ --- ]]
[[ signed char*->char ][ !!! *3* !!! ][ 88 ][ 10 ][ 8 ]]
[[ signed char*->signed char ][ !!! *2* !!! ][ 87 ][ 10 ][ 7 ]]
[[ signed char*->unsigned char ][ !!! *3* !!! ][ 87 ][ 9 ][ 13 ]]
[[ signed char*->int ][ !!! *6* !!! ][ 104 ][ 20 ][ 14 ]]
[[ signed char*->short ][ !!! *6* !!! ][ 105 ][ 21 ][ 14 ]]
[[ signed char*->long int ][ !!! *6* !!! ][ 104 ][ 20 ][ 15 ]]
[[ signed char*->long long ][ !!! *6* !!! ][ 106 ][ 20 ][ 14 ]]
[[ signed char*->unsigned int ][ !!! *6* !!! ][ 99 ][ 20 ][ 14 ]]
[[ signed char*->unsigned short ][ !!! *6* !!! ][ 100 ][ 18 ][ 14 ]]
[[ signed char*->unsigned long int ][ !!! *6* !!! ][ 102 ][ 23 ][ 14 ]]
[[ signed char*->unsigned long long ][ !!! *6* !!! ][ 103 ][ 20 ][ 14 ]]
[[ signed char*->bool ][ !!! *3* !!! ][ 99 ][ 18 ][ 7 ]]
[[ signed char*->float ][ !!! *18* !!! ][ 159 ][ 60 ][ 32 ]]
[[ signed char*->double ][ !!! *18* !!! ][ 203 ][ 95 ][ 57 ]]
[[ signed char*->long double ][ 129 ][ 213 ][ 97 ][ !!! *56* !!! ]]
[[ signed char*->string ][ !!! *14* !!! ][ 105 ][ 22 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 109 ][ 22 ][ --- ]]
[[ float->double ][ !!! *<1* !!! ][ 226 ][ 104 ][ --- ]]
[[ double->double ][ !!! *<1* !!! ][ 229 ][ 103 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 225 ][ 115 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 227 ][ 115 ][ --- ]]
[[ char->unsigned char ][ !!! *<1* !!! ][ 90 ][ 8 ][ --- ]]
[[ char->signed char ][ !!! *<1* !!! ][ 84 ][ 8 ][ --- ]]
[[ unsigned char->char ][ !!! *<1* !!! ][ 88 ][ 8 ][ --- ]]
[[ signed char->char ][ !!! *<1* !!! ][ 89 ][ 8 ][ --- ]]
]
[endsect]
[section gcc-4.6][table:id Performance Table (gcc-4.6)
[[From->To] [lexical_cast] [std::stringstream with construction] [std::stringstream without construction][scanf/printf]]
[[ string->char ][ !!! *<1* !!! ][ 94 ][ 8 ][ 7 ]]
[[ string->signed char ][ !!! *<1* !!! ][ 96 ][ 9 ][ 7 ]]
[[ string->unsigned char ][ !!! *<1* !!! ][ 96 ][ 8 ][ 13 ]]
[[ string->int ][ !!! *3* !!! ][ 110 ][ 18 ][ 16 ]]
[[ string->short ][ !!! *3* !!! ][ 111 ][ 18 ][ 16 ]]
[[ string->long int ][ !!! *3* !!! ][ 109 ][ 18 ][ 15 ]]
[[ string->long long ][ !!! *3* !!! ][ 111 ][ 18 ][ 15 ]]
[[ string->unsigned int ][ !!! *3* !!! ][ 110 ][ 20 ][ 15 ]]
[[ string->unsigned short ][ !!! *3* !!! ][ 111 ][ 18 ][ 15 ]]
[[ string->unsigned long int ][ !!! *3* !!! ][ 109 ][ 18 ][ 15 ]]
[[ string->unsigned long long ][ !!! *3* !!! ][ 114 ][ 19 ][ 15 ]]
[[ string->bool ][ !!! *<1* !!! ][ 106 ][ 17 ][ 8 ]]
[[ string->float ][ !!! *13* !!! ][ 175 ][ 70 ][ 33 ]]
[[ string->double ][ !!! *14* !!! ][ 182 ][ 81 ][ 58 ]]
[[ string->long double ][ 118 ][ 190 ][ 87 ][ !!! *58* !!! ]]
[[ char->string ][ !!! *8* !!! ][ 118 ][ 21 ][ 12 ]]
[[ unsigned char->string ][ !!! *8* !!! ][ 109 ][ 18 ][ 16 ]]
[[ signed char->string ][ !!! *8* !!! ][ 108 ][ 18 ][ 12 ]]
[[ int->string ][ 20 ][ 121 ][ 21 ][ !!! *16* !!! ]]
[[ short->string ][ !!! *15* !!! ][ 120 ][ 22 ][ 17 ]]
[[ long int->string ][ !!! *15* !!! ][ 120 ][ 22 ][ 16 ]]
[[ long long->string ][ !!! *15* !!! ][ 120 ][ 22 ][ 17 ]]
[[ unsigned int->string ][ !!! *15* !!! ][ 120 ][ 22 ][ 16 ]]
[[ unsigned short->string ][ !!! *15* !!! ][ 120 ][ 22 ][ 18 ]]
[[ unsigned long int->string ][ 16 ][ 118 ][ 22 ][ !!! *15* !!! ]]
[[ unsigned long long->string ][ !!! *15* !!! ][ 117 ][ 21 ][ 17 ]]
[[ bool->string ][ !!! *8* !!! ][ 117 ][ 23 ][ 10 ]]
[[ float->string ][ 77 ][ 218 ][ 105 ][ !!! *50* !!! ]]
[[ double->string ][ 108 ][ 247 ][ 129 ][ !!! *73* !!! ]]
[[ long double->string ][ 120 ][ 250 ][ 131 ][ !!! *79* !!! ]]
[[ char*->char ][ !!! *2* !!! ][ 99 ][ 9 ][ 7 ]]
[[ char*->signed char ][ !!! *2* !!! ][ 98 ][ 9 ][ 8 ]]
[[ char*->unsigned char ][ !!! *2* !!! ][ 98 ][ 9 ][ 13 ]]
[[ char*->int ][ !!! *6* !!! ][ 115 ][ 22 ][ 15 ]]
[[ char*->short ][ !!! *6* !!! ][ 114 ][ 22 ][ 15 ]]
[[ char*->long int ][ !!! *6* !!! ][ 114 ][ 22 ][ 16 ]]
[[ char*->long long ][ !!! *6* !!! ][ 119 ][ 22 ][ 15 ]]
[[ char*->unsigned int ][ !!! *6* !!! ][ 114 ][ 20 ][ 15 ]]
[[ char*->unsigned short ][ !!! *6* !!! ][ 116 ][ 20 ][ 15 ]]
[[ char*->unsigned long int ][ !!! *6* !!! ][ 117 ][ 22 ][ 15 ]]
[[ char*->unsigned long long ][ !!! *6* !!! ][ 118 ][ 22 ][ 15 ]]
[[ char*->bool ][ !!! *3* !!! ][ 113 ][ 18 ][ 8 ]]
[[ char*->float ][ !!! *15* !!! ][ 180 ][ 78 ][ 32 ]]
[[ char*->double ][ !!! *16* !!! ][ 185 ][ 89 ][ 58 ]]
[[ char*->long double ][ 119 ][ 193 ][ 91 ][ !!! *60* !!! ]]
[[ unsigned char*->char ][ !!! *2* !!! ][ 99 ][ 9 ][ 8 ]]
[[ unsigned char*->signed char ][ !!! *2* !!! ][ 99 ][ 10 ][ 8 ]]
[[ unsigned char*->unsigned char ][ !!! *2* !!! ][ 100 ][ 9 ][ 15 ]]
[[ unsigned char*->int ][ !!! *6* !!! ][ 118 ][ 22 ][ 15 ]]
[[ unsigned char*->short ][ !!! *6* !!! ][ 117 ][ 26 ][ 15 ]]
[[ unsigned char*->long int ][ !!! *6* !!! ][ 119 ][ 21 ][ 15 ]]
[[ unsigned char*->long long ][ !!! *6* !!! ][ 118 ][ 21 ][ 14 ]]
[[ unsigned char*->unsigned int ][ !!! *6* !!! ][ 115 ][ 22 ][ 14 ]]
[[ unsigned char*->unsigned short ][ !!! *6* !!! ][ 117 ][ 20 ][ 15 ]]
[[ unsigned char*->unsigned long int ][ !!! *6* !!! ][ 115 ][ 21 ][ 15 ]]
[[ unsigned char*->unsigned long long ][ !!! *6* !!! ][ 117 ][ 22 ][ 15 ]]
[[ unsigned char*->bool ][ !!! *3* !!! ][ 112 ][ 18 ][ 8 ]]
[[ unsigned char*->float ][ !!! *15* !!! ][ 181 ][ 78 ][ 33 ]]
[[ unsigned char*->double ][ !!! *16* !!! ][ 185 ][ 92 ][ 59 ]]
[[ unsigned char*->long double ][ 120 ][ 190 ][ 89 ][ !!! *58* !!! ]]
[[ unsigned char*->string ][ !!! *14* !!! ][ 121 ][ 22 ][ --- ]]
[[ signed char*->char ][ !!! *2* !!! ][ 99 ][ 9 ][ 9 ]]
[[ signed char*->signed char ][ !!! *2* !!! ][ 98 ][ 9 ][ 8 ]]
[[ signed char*->unsigned char ][ !!! *2* !!! ][ 98 ][ 9 ][ 14 ]]
[[ signed char*->int ][ !!! *6* !!! ][ 119 ][ 22 ][ 16 ]]
[[ signed char*->short ][ !!! *6* !!! ][ 115 ][ 22 ][ 15 ]]
[[ signed char*->long int ][ !!! *6* !!! ][ 119 ][ 22 ][ 15 ]]
[[ signed char*->long long ][ !!! *6* !!! ][ 117 ][ 22 ][ 15 ]]
[[ signed char*->unsigned int ][ !!! *6* !!! ][ 117 ][ 23 ][ 15 ]]
[[ signed char*->unsigned short ][ !!! *6* !!! ][ 117 ][ 21 ][ 14 ]]
[[ signed char*->unsigned long int ][ !!! *7* !!! ][ 119 ][ 24 ][ 15 ]]
[[ signed char*->unsigned long long ][ !!! *6* !!! ][ 116 ][ 22 ][ 15 ]]
[[ signed char*->bool ][ !!! *3* !!! ][ 111 ][ 18 ][ 8 ]]
[[ signed char*->float ][ !!! *16* !!! ][ 180 ][ 78 ][ 33 ]]
[[ signed char*->double ][ !!! *16* !!! ][ 185 ][ 89 ][ 59 ]]
[[ signed char*->long double ][ 120 ][ 191 ][ 91 ][ !!! *59* !!! ]]
[[ signed char*->string ][ !!! *14* !!! ][ 122 ][ 23 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 120 ][ 22 ][ --- ]]
[[ float->double ][ !!! *<1* !!! ][ 242 ][ 115 ][ --- ]]
[[ double->double ][ !!! *<1* !!! ][ 243 ][ 115 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 265 ][ 141 ][ --- ]]
[[ int->int ][ !!! *<1* !!! ][ 266 ][ 140 ][ --- ]]
[[ char->unsigned char ][ !!! *<1* !!! ][ 95 ][ 8 ][ --- ]]
[[ char->signed char ][ !!! *<1* !!! ][ 95 ][ 8 ][ --- ]]
[[ unsigned char->char ][ !!! *<1* !!! ][ 94 ][ 8 ][ --- ]]
[[ signed char->char ][ !!! *<1* !!! ][ 94 ][ 8 ][ --- ]]
]
[endsect]
[/ END of section, generated by performance measuring program ]
[endsect]
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