forked from boostorg/core
48 lines
1.9 KiB
Plaintext
48 lines
1.9 KiB
Plaintext
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[/
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/ Copyright (c) 2022 Andrey Semashev
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/
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/ Distributed under the Boost Software License, Version 1.0. (See accompanying
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/ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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/]
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[section:snprintf snprintf]
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[simplesect Authors]
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* Andrey Semashev
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[endsimplesect]
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[section Header <boost/core/snprintf.hpp>]
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The header `<boost/core/snprintf.hpp>` provides portable definition of [@https://en.cppreference.com/w/c/io/fprintf `snprintf`],
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`vsnprintf` and their corresponding `wchar_t` counterparts. On a platform that supports these functions in the standard library,
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these definitions are equivalent to the standard functions. On other platforms (mainly, older MSVC versions) these functions
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are emulated through non-standard functions that have similar behavior.
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Depending on the standard library, certain implementation differences are exposed to the user:
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* Any non-standard behavior with respect to string format description are not hidden by the emulation.
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* Returned value of `boost::core::snprintf` in case if the output buffer is too small may not be equal to the number of characters
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that would have been written if the buffer was large enough. It is, however, equal or larger than the buffer size,
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which still allows the caller to detect the buffer overflow condition. The formatted output is still properly null-terminated
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in this case.
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[note Unlike `snprintf`, `swprintf` does not return the number of characters to be written if the output buffer is too small
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but returns -1 instead. Furthermore, `swprintf` may or may not produce characters in the output buffer in this case.]
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[section Example]
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``
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char buf[10];
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int n = boost::core::snprintf(buf, sizeof(buf), "%d", i);
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if (n < 0)
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throw std::runtime_error("Formatting error");
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if (n >= sizeof(buf))
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throw std::runtime_error("Formatting buffer overflow");
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``
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[endsect]
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[endsect]
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[endsect]
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