标准库头文件 <charconv> (C++17)

 

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标准库头文件

语言支持
<cstddef> <cstdlib> <version> (C++20) <limits> <climits>	<cfloat> <cstdint> (C++11) <stdfloat> (C++23) <new> <typeinfo>	<source_location> (C++20) <exception> <initializer_list> (C++11) <compare> (C++20)	<coroutine> (C++20) <csignal> <csetjmp> <cstdarg>
概念
<concepts> (C++20)
诊断
<stdexcept> <stacktrace> (C++23)	<cassert>	<cerrno>	<system_error> (C++11)
内存管理
<memory>	<memory_resource> (C++17)	<scoped_allocator> (C++11)
元编程
<type_traits> (C++11)	<ratio> (C++11)
通用工具
<utility> <tuple> (C++11) <optional> (C++17) <variant> (C++17)	<any> (C++17) <debugging> (C++26) <expected> (C++23) <bitset>	<functional> <typeindex> (C++11) <execution> (C++17)	<charconv> (C++17) <format> (C++20) <bit> (C++20)
字符串
<string_view> (C++17) <string>	<cctype> <cwctype>	<cstring> <cwchar>	<cuchar> (C++11)
容器
<array> (C++11) <deque> <forward_list> (C++11) <list>	<vector> <map> <set> <unordered_map> (C++11)	<unordered_set> (C++11) <queue> <stack> <flat_map> (C++23)	<flat_set> (C++23) <span> (C++20) <mdspan> (C++23) <inplace_vector> (C++26)
迭代器
<iterator>
范围
<ranges> (C++20)	<generator> (C++23)
算法
<algorithm>	<numeric>
数值
<cfenv> (C++11) <complex>	<random> (C++11) <valarray>	<cmath> <linalg> (C++26)	<numbers> (C++20)
时间
<chrono> (C++11)	<ctime>
本地化
<locale>	<clocale>	<codecvt> (C++11/17/26*)	<text_encoding> (C++26)
输入/输出
<iosfwd> <iostream> <ios> <streambuf>	<istream> <ostream> <iomanip> <print> (C++23)	<sstream> <spanstream> (C++23) <fstream> <syncstream> (C++20)	<filesystem> (C++17) <cstdio> <cinttypes> (C++11) <strstream> (C++98/26*)
正则表达式
<regex> (C++11)
并发支持
<stop_token> (C++20) <thread> (C++11) <atomic> (C++11) <rcu> (C++26)	<stdatomic.h> (C++23) <mutex> (C++11) <shared_mutex> (C++14)	<condition_variable> (C++11)   <semaphore> (C++20) <latch> (C++20)	<barrier> (C++20) <future> (C++11) <hazard_pointer> (C++26)
C 兼容性
<cstdbool> (C++11/17/20*)   <ccomplex> (C++11/17/20*)	<ctgmath> (C++11/17/20*)	<cstdalign> (C++11/17/20*)	<ciso646> (直到 C++20)

 

此头文件是 字符串 库的一部分。

类
chars_format (C++17)	指定 std::to_chars 和 std::from_chars 的格式 (枚举)
from_chars_result (C++17)	std::from_chars 的返回类型 (类)
to_chars_result (C++17)	std::to_chars 的返回类型 (类)
函数
from_chars (C++17)	将字符序列转换为整数或浮点数 (函数)
to_chars (C++17)	将整数或浮点数转换为字符序列 (函数)

概述

namespace std {
  // floating-point format for primitive numerical conversion
  enum class chars_format {
    scientific = /* unspecified */,
    fixed = /* unspecified */,
    hex = /* unspecified */,
    general = fixed | scientific
  };
 
 
  // primitive numerical output conversion
  struct to_chars_result { // freestanding
    char* ptr;
    errc ec;
    friend bool operator==(const to_chars_result&, const to_chars_result&) = default;
    constexpr explicit operator bool() const noexcept { return ec == errc{}; }
  };
 
  constexpr
  to_chars_result to_chars(char* first, char* last, // freestanding
                           /* integer-type */ value, int base = 10);
  to_chars_result to_chars(char* first, char* last, // freestanding
                           bool value, int base = 10) = delete;
  to_chars_result to_chars(char* first, char* last, // freestanding-deleted
                           /* floating-point-type */ value);
  to_chars_result to_chars(char* first, char* last, // freestanding-deleted
                           /* floating-point-type */ value, chars_format fmt);
  to_chars_result to_chars(char* first, char* last, // freestanding-deleted
                           /* floating-point-type */ value,
                           chars_format fmt, int precision);
 
  // primitive numerical input conversion
  struct from_chars_result { // freestanding
    const char* ptr;
    errc ec;
    friend bool operator==(const from_chars_result&, const from_chars_result&) = default;
    constexpr explicit operator bool() const noexcept { return ec == errc{}; }
  };
 
  constexpr
  from_chars_result from_chars(const char* first, // freestanding
                               const char* last, /* integer-type */& value,
                               int base = 10);
  from_chars_result from_chars(const char* first, // freestanding-deleted
                               const char* last, /* floating-point-type */& value,
                               chars_format fmt = chars_format::general);
}