Overview
-Description
-Charconv is a collection of parsing functions that are locale-independent, non-allocating, and non-throwing.
-Usage Examples
-#include <boost/charconv.hpp>
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-const char* buffer = "42";
-int v = 0;
-auto r = boost::charconv::from_chars(buffer, buffer + std::strlen(buffer), v);
-assert(r == 42);Supported Compilers
--
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GCC 5 or later with
--std=c++11or above
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Clang 3.9 or later with
--std=c++11or above
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Visual Studio 2015, 2017, 2019
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Tested on Github Actions.
-from_chars
-from_chars overview
-struct from_chars_result
-{
- const char* ptr;
- int ec;
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- friend constexpr bool operator==(const from_chars_result& lhs, const from_chars_result& rhs) noexcept
- friend constexpr bool operator!=(const from_chars_result& lhs, const from_chars_result& rhs) noexcept
-}
-
-template <typename Integral>
-BOOST_CXX14_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, Integral& value, int base = 10) noexcept;
-
-BOOST_CXX14_CONSTEXPR from_chars_result from_chars<bool>(const char* first, const char* last, bool& value, int base) = delete;from_chars_result
--
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ptr - points to the first character not matching the pattern, or has the value of last if all characters are successfully parsed.
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ec - the error code. Valid values for <cerrno> are:
----
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0 - successful parsing
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EINVAL - invalid argument (e.g. parsing a negative number into an unsigned type)
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ERANGE - result out of range (e.g. overflow)
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operator== - compares the values of ptr and ec for equality
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operator!- - compares the value of ptr and ec for inequality
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from_chars
--
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first, last - valid range to parse
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value - where the output is stored upon successful parsing
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base - the integer base to use. Must be between 2 and 36 inclusive
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from_chars for integral types is constexpr when compiled using
--std=c++14or newer---
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One known exception is GCC 5 which does not support constexpr comparison of const char*.
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from_chars for integral types
--
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All built-in integral types are allowed except bool which is deleted
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These function have been tested to support
-int128andunsigned int128when compiling with-std=gnu++11or newer
-
Examples
-Basic usage
-const char* buffer = "42";
-int v = 0;
-from_chars_result r = boost::charconv::from_chars(buffer, buffer + std::strlen(buffer), v);
-assert(r.ec == 0);
-assert(v == 42);Hexadecimal
-const char* buffer = "2a";
-unsigned v = 0;
-auto r = boost::charconv::from_chars(buffer, buffer + std::strlen(buffer), v, 16);
-assert(r.ec == 0);
-assert(v == 42);EINVAL
-const char* buffer = "-123";
-unsigned v = 0;
-auto r = boost::charconv::from_chars(buffer, buffer + std::strlen(buffer), v);
-assert(r.ec, EINVAL);
-assert(v == 0);In the event of EINVAL v is not set by from_chars
ERANGE
-const char* buffer = "1234";
-unsigned char v = 0;
-auto r = boost::charconv::from_chars(buffer, buffer + std::strlen(buffer), v);
-assert(r.ec == ERANGE);
-assert(v == 0)In the event of ERANGE v is not set by from_chars
Reference
-<boost/charconv/from_chars.hpp>
-Synopsis
-namespace boost {
-namespace charconv {
-
-struct from_chars_result;
-
-template <typename Integral>
-BOOST_CXX14_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, Integral& value, int base = 10) noexcept;
-
-// ...
-
-} // namespace charconv
-} // namespace boost<boost/charconv/to_chars.hpp>
-Synopsis
-namespace boost {
-namespace charconv {
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-struct to_chars_result;
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-template<class Integral>
-to_chars_result to_chars( char* first, char* last, Integral value, int base = 10 );
-
-// ...
-
-} // namespace charconv
-} // namespace boost<boost/charconv.hpp>
-This convenience header includes all headers previously -mentioned.
-Copyright and License
-This documentation is copyright 2022-2023 Peter Dimov and Matt Borland and is distributed under -the Boost Software License, Version 1.0.
-