cppreference.com > C++ Strings > replace
replace
Syntax:
  #include <string>
  string& replace( size_type index, size_type num, const string& str );
  string& replace( size_type index1, size_type num1, const string& str, size_type index2, size_type num2 );
  string& replace( size_type index, size_type num, const char* str );
  string& replace( size_type index, size_type num1, const char* str, size_type num2 );
  string& replace( size_type index, size_type num1, size_type num2, char ch );
  string& replace( iterator start, iterator end, const string& str );
  string& replace( iterator start, iterator end, const char* str );
  string& replace( iterator start, iterator end, const char* str, size_type num );
  string& replace( iterator start, iterator end, size_type num, char ch );

The function replace() either:

For example, the following code displays the string "They say he carved it himself...find your soul-mate, Homer."

   string s = "They say he carved it himself...from a BIGGER spoon";
   string s2 = "find your soul-mate, Homer.";
   s.replace( 32, s2.length(), s2 );
   cout << s << endl;