C++11 case insensitive comparison of beginning of a string (unicode)

Question

I have to check if the particular string begins with another one. Strings are encoded using utf8, and a comparison should be case insensitive.

I know that this is ve

Answer 1

Using the stl regex classes you could do something like the following snippet. Unfortunately its not utf8. Changing str2 to std::wstring str2 = L"hello World" results in a lot of conversion warnings. Making str1 an std::wchar doesn't work at all, since std::regex doesn't allow a whar input (as far as i can see).

#include 
#include 
#include 

int main()
{
    //The input strings
    std::string str1 = "Hello";
    std::string str2 = "hello World";

    //Define the regular expression using case-insensitivity
    std::regex regx(str1, std::regex_constants::icase);

    //Only search at the beginning 
    std::regex_constants::match_flag_type fl = std::regex_constants::match_continuous;

    //display some output
    std::cout << std::boolalpha << std::regex_search(str2.begin(), str2.end(), regx, fl) << std::endl;

    return 0;
}