C++ get the length of LPCWSTR and LPVOID

Question

The winapi function WinHttpSendRequest() wants the size of the second parameter in the third one and the size of the fourth parameter in the fifth one.
How can I calculate it?
I have a function wrapped around it and I pass the strings directly, about like this:

void Req(LPCWSTR headers, LPVOID body) {
    WinHttpSendRequest( hRequest, headers, (DWORD)strlen(headers), body, (DWORD)strlen(body), 0, 0 );
}
Req(L"User-Agent: blabla/1.0\r\nConnection: Keep Alive", "asdf=qwer&abcd=1234);

The above code doesn't work. :/
I hope you can help me out.

Solution

.You need to use wcslen instead of strlen for wide-strings.