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std::ctype_byname

来自 cppreference.cn
< cpp‎ | locale
 
C++
 
文本处理库
 
本地化库
 
定义于头文件 <locale>
template< class CharT >
class ctype_byname : public std::ctype<CharT>;

std::ctype_byname 是一个 std::ctype facet，它封装了在其构造时指定的区域设置的字符分类规则。

目录

[编辑] 特化

标准库保证提供以下特化

定义于头文件 <locale>
std::ctype_byname<char> 提供窄字符分类（使用表查找进行字符分类）
std::ctype_byname<wchar_t> 提供宽字符分类

[编辑] 嵌套类型

类型 定义
mask typename std::ctype<CharT>::mask

[编辑] 成员函数

(构造函数)
 构造一个新的 ctype_byname facet
(public member function) [编辑]
(析构函数)
 销毁一个 ctype_byname facet
(protected member function) [编辑]
[编辑]

std::ctype_byname::ctype_byname

explicit ctype_byname( const char* name, std::size_t refs = 0 );
explicit ctype_byname( const std::string& name, std::size_t refs = 0 );
 (自 C++11 起)

为具有 name 的区域设置构造一个新的 std::ctype_byname facet。

refs 用于资源管理：如果 refs == 0，则当持有它的最后一个 std::locale 对象被销毁时，实现会销毁该 facet。 否则，该对象不会被销毁。

参数

name - 区域设置的名称
refs - 链接到 facet 的引用数
[编辑]

std::ctype_byname::~ctype_byname

protected:
~ctype_byname();

销毁 facet。

继承自 std::ctype<CharT> (仅当 CharT 不是 char 时)

嵌套类型

类型 定义
char_type CharT

数据成员

成员 描述
std::locale::id id [static] facet 的标识符

成员函数

 调用 do_is
(public member function of std::ctype<CharT>) [编辑]
 调用 do_scan_is
(public member function of std::ctype<CharT>) [编辑]
 调用 do_scan_not
(public member function of std::ctype<CharT>) [编辑]
 toupper
(public member function of std::ctype<CharT>) [编辑]
 tolower
(public member function of std::ctype<CharT>) [编辑]
 调用 do_widen
(public member function of std::ctype<CharT>) [编辑]
 调用 do_narrow
(public member function of std::ctype<CharT>) [编辑]

受保护的成员函数

[virtual]
 将一个或多个字符转换为大写
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 将一个或多个字符转换为小写
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 将一个或多个字符从 char 转换为 CharT
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 将一个或多个字符从 CharT 转换为 char
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 分类一个字符或字符序列
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 在序列中定位第一个符合给定分类的字符
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 在序列中定位第一个不符合给定分类的字符
(virtual protected member function of std::ctype<CharT>) [编辑]

继承自 std::ctype<char> (仅当 CharT 是 char 时)

嵌套类型

类型 定义
char_type char

数据成员

成员 描述
std::locale::id id [static] facet 的标识符
const std::size_t table_size [static] 分类表的大小，至少为 256

成员函数

 获取字符分类表
(public member function of std::ctype<char>) [编辑]
[static]
 获取 “C” 区域设置字符分类表
(public static member function of std::ctype<char>) [编辑]
 is
(public member function of std::ctype<char>) [编辑]
 scan_is
(public member function of std::ctype<char>) [编辑]
 scan_not
(public member function of std::ctype<char>) [编辑]
 toupper
(public member function of std::ctype<CharT>) [编辑]
 tolower
(public member function of std::ctype<CharT>) [编辑]
 调用 do_widen
(public member function of std::ctype<CharT>) [编辑]
 调用 do_narrow
(public member function of std::ctype<CharT>) [编辑]

受保护的成员函数

[virtual]
 将一个或多个字符转换为大写
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 将一个或多个字符转换为小写
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 将一个或多个字符从 char 转换为 CharT
(virtual protected member function of std::ctype<CharT>) [编辑]
[virtual]
 将一个或多个字符从 CharT 转换为 char
(virtual protected member function of std::ctype<CharT>) [编辑]

继承自 std::ctype_base

嵌套类型

类型 定义
mask 未指明的 BitmaskType 类型（枚举，整数类型或 bitset）

成员常量

space
[static]
 mask 的值，用于标识空白字符分类
(public static member constant)
print
[static]
 mask 的值，用于标识可打印字符分类
(public static member constant)
cntrl
[static]
 mask 的值，用于标识控制字符分类
(public static member constant)
upper
[static]
 mask 的值，用于标识大写字符分类
(public static member constant)
lower
[static]
 mask 的值，用于标识小写字符分类
(public static member constant)
alpha
[static]
 mask 的值，用于标识字母字符分类
(public static member constant)
digit
[static]
 mask 的值，用于标识数字字符分类
(public static member constant)
punct
[static]
 mask 的值，用于标识标点字符分类
(public static member constant)
xdigit
[static]
 mask 的值，用于标识十六进制数字字符分类
(public static member constant)
blank
[static] (C++11)
 mask 的值，用于标识空白字符分类
(public static member constant)
alnum
[static]
 alpha | digit
(public static member constant)
graph
[static]
 alnum | punct
(public static member constant)

[编辑] 注解

std::ctype_byname<char> 在 <locale> 的概要中被错误地声明为显式特化，并且该声明已通过 LWG issue 1298 的决议移除，但它仍然是一个必需的特化，就像 std::ctype_byname<wchar_t> 一样。

[编辑] 示例

运行此代码
#include <iostream>
#include <locale>
 
int main()
{
    wchar_t c = L'\u00de'; // capital letter thorn
 
    std::locale loc("C");
 
    std::cout << "isupper('Þ', C locale) returned "
              << std::boolalpha << std::isupper(c, loc) << '\n';
 
    loc = std::locale(loc, new std::ctype_byname<wchar_t>("en_US.utf8"));
 
    std::cout << "isupper('Þ', C locale with Unicode ctype) returned "
              << std::boolalpha << std::isupper(c, loc) << '\n';
}

输出

isupper('Þ', C locale) returned false
isupper('Þ', C locale with Unicode ctype) returned true

[编辑] 缺陷报告

以下行为变更缺陷报告被追溯应用于先前发布的 C++ 标准。

DR 应用于 已发布行为 正确行为
LWG 16 C++98 显式特化 std::ctype_byname<char> 的定义
错误指定了 do_narrow 的名称和参数列表		 已更正
LWG 616 C++98 在 mask 的定义中缺少 typename 消歧义符 已添加

[编辑] 参见

 ctype
(class template) [编辑]
 std::ctype 对类型 char 的特化
(class template specialization) [编辑]
取自“https://cppreference.cn/mwiki/index.php?title=cpp/locale/ctype_byname&oldid=177977”