how to extract substring from string in c++

// CPP program to illustrate substr() 
#include <string.h> 
#include <iostream> 
using namespace std; 
  
int main() 
{ 
    // Take any string 
    string s1 = "Geeks"; 
  
    // Copy three characters of s1 (starting  
    // from position 1) 
    string r = s1.substr(1, 3); 
  
    // prints the result 
    cout << "String is: " << r; 
  
    return 0; 
}