std::ctype::tolower
STD：：Ctype：：Tolower，STD：：Ctype：：do[医]收费人
| Defined in header | | |
|---|---|---|
| public: CharT tolower( CharT c ) const; | (1) | |
| public: const CharT* tolower( CharT* beg, const CharT* end ) const; | (2) | |
| protected: virtual CharT do_tolower( CharT c ) const; | (3) | |
| protected: virtual const CharT* do_tolower( CharT* beg, const CharT* end ) const; | (4) | |
1，2%29的公共成员函数，调用受保护的虚拟成员函数。do_tolower最派生的类。
3%29转换字符c如果此区域设置定义了小写窗体，则为小写。
4%29对字符数组中的每个字符[beg, end)，如果存在小写窗体，则将字符替换为该小写窗体。
参数
| c | - | character to convert |
|---|---|---|
| beg | - | pointer to the first character in an array of characters to convert |
| end | - | one past the end pointer for the array of characters to convert |
返回值
1，3%29小写字符或c如果此区域设置没有列出小写窗体。
2，4%29end...
注记
这个函数只能执行01：1的字符映射，例如，希腊大写字母%27Σ%27有两个小写形式，取决于单词中的位置：%27σ%27和%27%100。打电话给do_tolower在这种情况下，无法使用它获得正确的小写形式。
例
二次
#include <locale>
#include <iostream>
void try_lower(const std::ctype<wchar_t>& f, wchar_t c)
{
wchar_t up = f.tolower(c
if (up != c) {
std::wcout << "Lower case form of \'" << c << "' is " << up << '\n';
} else {
std::wcout << '\'' << c << "' has no lower case form\n";
}
}
int main()
{
std::locale::global(std::locale("en_US.utf8")
std::wcout.imbue(std::locale()
std::wcout << "In US English UTF-8 locale:\n";
auto& f = std::use_facet<std::ctype<wchar_t>>(std::locale()
try_lower(f, L'Σ'
try_lower(f, L'Ɛ'
try_lower(f, L'Ａ'
std::wstring str = L"HELLo, wORLD!";
std::wcout << "Lowercase form of the string '" << str << "' is ";
f.tolower(&str[0], &str[0] + str.size()
std::wcout << "'" << str << "'\n";
}
二次
产出：
二次
In US English UTF-8 locale:
Lower case form of 'Σ' is σ
Lower case form of 'Ɛ' is ɛ
Lower case form of 'Ａ' is ａ
Lowercase form of the string 'HELLo, wORLD!' is 'hello, world!'
二次
另见
| toupper | invokes do_toupper (public member function) |
|---|---|
| tolower | converts a character to lowercase (function) |
| towlower | converts a wide character to lowercase (function) |
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