std::collate::transform
整理：：转换，做[医]变换
| Defined in header | | |
|---|---|---|
| public: string_type transform( const CharT* low, const CharT* high ) const; | (1) | |
| protected: virtual string_type do_transform( const CharT* low, const CharT* high ) const; | (2) | |
1%29公共成员函数，调用受保护的虚拟成员函数do_transform最派生的类。
2%29转换字符序列[low, high)与字符串进行比较，按字典顺序计算为%28例如。带着operator<对于字符串%29和调用的结果transform()在另一个字符串上，产生与调用do_compare()在同样的两条线上。
参数
| low | - | pointer to the first character in the sequence to transform |
|---|---|---|
| high | - | one past the end pointer for the sequence to transform |
返回值
该字符串被转换，使转换后的字符串的字典比较可以被使用，而不是对原始字符串进行校对。在“C”区域设置中，返回的字符串是[low, high)在其他语言环境中，返回的字符串的内容是实现定义的，大小可能要长得多。
注记
除了在排序规则中使用之外，转换后的字符串的特定实现格式还可以在STD：：regex[医]性状<>：转换[医]初等，它能够提取等价类信息。
例
二次
#include <iostream>
#include <iomanip>
#include <locale>
int main()
{
std::locale::global(std::locale("sv_SE.utf8")
auto& f = std::use_facet<std::collate<wchar_t>>(std::locale()
std::wstring in1 = L"\u00e4ngel";
std::wstring in2 = L"\u00e5r";
std::wstring out1 = f.transform(&in1[0], &in1[0] + in1.size()
std::wstring out2 = f.transform(&in2[0], &in2[0] + in2.size()
std::wcout << "In the Swedish locale: ";
if(out1 < out2)
std::wcout << in1 << " before " << in2 << '\n';
else
std::wcout << in2 << " before " << in1 << '\n';
std::wcout << "In lexicographic comparison: ";
if(in1 < in2)
std::wcout << in1 << " before " << in2 << '\n';
else
std::wcout << in2 << " before " << in1 << '\n';
}
二次
产出：
二次
In the Swedish locale: år before ängel
In lexicographic comparison: ängel before år
二次
另见
| strxfrm | transform a string so that strcmp would produce the same result as strcoll (function) |
|---|---|
| wcsxfrm | transform a wide string so that wcscmp would produce the same result as wcscoll (function) |
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