Difference between revisions of "cpp/string/multibyte/wctob"
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| − | + | 窄化宽字符 {{tt|c}} ，若其多字节字符等价版本在初始迁移状态为单字节。 | |
| − | + | 这典型地对来自 ASCII 字符集的字符可行，因为大多数多字节编码（例如 UTF-8 ）用单字节编码那些字符。 | |
| − | === | + | ===参数=== |
{{par begin}} | {{par begin}} | ||
| − | {{par | c | | + | {{par | c |要窄化的宽字符}} |
{{par end}} | {{par end}} | ||
| − | === | + | ===返回值=== |
| − | {{ | + | 若 {{tt|c}} 在初始迁移状态不表示长度为 {{c|1}} 的多字节字符则为 {{lc|EOF}} 。 |
| − | + | 否则，为作为 {{c|unsigned char}} 的 {{tt|c}} 的单字节表示，转换为 {{c|int}} 。 | |
| − | === | + | ===示例=== |
{{example | {{example | ||
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| − | === | + | ===参阅=== |
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Revision as of 01:29, 10 October 2017
| Defined in header <cwchar>
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| int wctob( std::wint_t c ); |
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窄化宽字符 c ，若其多字节字符等价版本在初始迁移状态为单字节。
这典型地对来自 ASCII 字符集的字符可行，因为大多数多字节编码（例如 UTF-8 ）用单字节编码那些字符。
Contents |
参数
| c | - | 要窄化的宽字符 |
返回值
若 c 在初始迁移状态不表示长度为 1 的多字节字符则为 EOF 。
否则，为作为 unsigned char 的 c 的单字节表示，转换为 int 。
示例
Run this code
#include <clocale> #include <cwchar> #include <iostream> void try_narrowing(wchar_t c) { int cn = std::wctob(c); if(cn != EOF) std::cout << '\'' << c << "' narrowed to " << +cn << '\n'; else std::cout << '\'' << c << "' could not be narrowed\n"; } int main() { std::setlocale(LC_ALL, "th_TH.utf8"); std::cout << std::hex << std::showbase << "In Thai UTF-8 locale:\n"; try_narrowing(L'a'); try_narrowing(L'๛'); std::setlocale(LC_ALL, "th_TH.tis620"); std::cout << "In Thai TIS-620 locale:\n"; try_narrowing(L'a'); try_narrowing(L'๛'); }
Output:
In Thai UTF-8 locale: '0x61' narrowed to 0x61 '0xe5b' could not be narrowed In Thai TIS-620 locale: '0x61' narrowed to 0x61 '0xe5b' narrowed to 0xfb
参阅
| widens a single-byte narrow character to wide character, if possible (function) | |
| narrows characters (public member function of std::basic_ios<CharT,Traits>)
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invokes do_narrow (public member function of std::ctype<CharT>)
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| C documentation for wctob
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