std :: wstring长度 [英] std::wstring length

问题描述

std :: wstring.length（）函数的结果是什么，wchar_t（s）中的长度还是以符号的长度？为什么？

What is the result of std::wstring.length() function, the length in wchar_t(s) or the length in symbols? And why?

TCHAR r2[3];
r2[0] = 0xD834;  // D834, DD1E - musical G clef
r2[1] = 0xDD1E;  //
r2[2] = 0x0000;  // '/0'

std::wstring r = r2;

std::cout << "capacity: " << r.capacity() << std::endl;
std::cout << "length: "   << r.length()   << std::endl;
std::cout << "size: "     << r.size()     << std::endl;
std::cout << "max_size: " << r.max_size() << std::endl;

Output>

capacity: 351
length: 2
size: 2
max_size: 2147483646

推荐答案

std :: wstring :: size（）返回宽字符数字符串中的元素。这与字符数不同（正如你所注意到的那样）。

std::wstring::size() returns the number of wide-char elements in the string. This is not the same as the number of characters (as you correctly noticed).

不幸的是， std :: basic_string 模板（因此它的实例化，例如 std :: string 和 std :: wstring ）是encoding-不可知。在这个意义上，它实际上只是一个字符串的模板，而不是字符串。

Unfortunately, the std::basic_string template (and thus its instantiations, such as std::string and std::wstring) is encoding-agnostic. In this sense, it is actually just a template for a string of bytes and not a string of characters.

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