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

How about:

string s = "          "; // 10 spaces
string n = "123";
n.length() <= 10 ? s.replace(10 - n.length(), n.length(), s) : s = n;