How can I get the byte size of std::wstring?

问题

I am using std::wstring as my Unicode style string. Now I want to get the byte size of a wstring. If I use size() method of wstring, I just get the total number of chars in my wstring. But the byte should be size() * 2. Is there an official way to get this byte size? I don't want to use size() * 2 in my program.....

I want to use in RegSetValueExW as last parameter.

回答1:

Use str.size() * sizeof(wchar_t) or equivalent.

In fact, I can't think of any other platform besides Windows that has 2-byte wchar_t, 4 bytes is far more common.

回答2:

Why not :

( str.size() * sizeof(wchar_t) ) ;

Or :

( str.size() * sizeof(std::wstring::traits_type::char_type) ) ;

回答3:

std::wstring s = L"Howdy, world!";
//...
std::size_t bytes_count = s.size() * sizeof s[0];

回答4:

You can use wcslen function

MSDN link: http://msdn.microsoft.com/en-us/library/78zh94ax.aspx

Linux: http://linux.die.net/man/3/wcslen

来源：https://stackoverflow.com/questions/9278723/how-can-i-get-the-byte-size-of-stdwstring