Step: Brief Discussion :
#include <string>
iterator insert( iterator i, const char& ch );
string& insert( size_type index, const string& str );
string& insert( size_type index, const char* str );
string& insert( size_type index1, const string& str,
size_type index2, size_type num );
string& insert( size_type index, const char* str,
size_type num );
string& insert( size_type index, size_type
num, char ch );
void insert( iterator i, size_type num, const char& ch
);
void insert( iterator i, iterator start, iterator end );