Padding stl strings in C++

Question

I\'m using std::string and need to left pad them to a given width. What is the recommended way to do this in C++?

Sample input:

123
         


        

Answer 1

void padTo(std::string &str, const size_t num, const char paddingChar = ' ')
{
    if(num > str.size())
        str.insert(0, num - str.size(), paddingChar);
}

int main(int argc, char **argv)
{
    std::string str = "abcd";
    padTo(str, 10);
    return 0;
}