Check out example codes for "check if a string is substring of another c++". It will help you in understanding the concepts better.

Code Example 1

// CPP program to check if a string is 
// substring of other. 
#include <bits/stdc++.h> 
using namespace std; 
  
// Returns true if s1 is substring of s2 
int isSubstring(string s1, string s2) 
{ 
    int M = s1.length(); 
    int N = s2.length(); 
  
    /* A loop to slide pat[] one by one */
    for (int i = 0; i <= N - M; i++) { 
        int j; 
  
        /* For current index i, check for 
 pattern match */
        for (j = 0; j < M; j++) 
            if (s2[i + j] != s1[j]) 
                break; 
  
        if (j == M) 
            return i; 
    } 
  
    return -1; 
} 
  
/* Driver program to test above function */
int main() 
{ 
    string s1 = "for"; 
    string s2 = "geeksforgeeks"; 
    int res = isSubstring(s1, s2); 
    if (res == -1) 
        cout << "Not present"; 
    else
        cout << "Present at index " << res; 
    return 0; 
}

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