toupper()

#include <iostream>

void uppering(std::string &upIt);
int main()
{
    std::string word;
    for(;;)
    {
        std::cout << "Nastepny lancuch: ";
        getline(std::cin, word);
        if(word == "q")
            break;
        uppering(word);
        std::cout << word << "\n";
    }
    std::cout << "Do widzenia";
    return 0;
}
void uppering(std::string &upIt)
{
    int i = 0;
    while(upIt[i] != NULL)
    {
        upIt[i] = toupper(upIt[i]);
        i++;
    }
}