Program to print the longest common substring using C++

In this tutorial, we will be discussing a program to print the longest common substring.

For this we will be given two strings say A and B. We have to print the longest substring common to the two input strings A and B.

For example, if we are given with “HelloWorld” and “world book”. Then the longest common substring, in this case, will be the “world”.

Example

#include <iostream> #include <stdlib.h> #include <string.h> using namespace std; void print_lstring(char* X, char* Y, int m, int n){    int longest[m + 1][n + 1];    int len = 0;    int row, col;    for (int i = 0; i <= m; i++) {       for (int j = 0; j <= n; j++) {          if (i == 0 || j == 0)             longest[i][j] = 0;          else if (X[i - 1] == Y[j - 1]) {             longest[i][j] = longest[i - 1][j - 1] + 1;             if (len < longest[i][j]) {                len = longest[i][j];                row = i;                col = j;             }          }          else             longest[i][j] = 0;          }       }       if (len == 0) {          cout << "There exists no common substring";       return;    }    char* final_str = (char*)malloc((len + 1) * sizeof(char));    while (longest[row][col] != 0) {       final_str[--len] = X[row - 1];       row--;       col--;    }    cout << final_str; } int main(){    char X[] = "helloworld";    char Y[] = "worldbook";    int m = strlen(X);    int n = strlen(Y);    print_lstring(X, Y, m, n);    return 0; }

Output

world