substring-code.c

#include <stdio.h>

// Code for Finding substring

// Function for checking substring

int search(char src[], char str[])
{
  int i, j, f;
  i = 0, j = 0;

  while (src[i] != '\0')
  {

    while (src[i] != str[0] && src[i] != '\0')
      i++;

    if (src[i] == '\0')
      return (-1);

    f = i;

    while (src[i] == str[j] && src[i] != '\0' && str[j] != '\0')
    {
      i++;
      j++;
    }

    if (str[j] == '\0')
      return (f);
    if (src[i] == '\0')
      return (-1);

    i = f + 1;
    j = 0;
  }
}

// Main function

void main()
{

// Declaring Variable
  char str1[100], str2[100];

  int i, l, temp = 0;

// Taking Input the string
  printf("Enter a string:");
  gets(str1);

// Taking Input substring to check
  printf("Enter substring to check in string:");
  gets(str2);

// Calling function
  int sub = search(str1, str2);

  if (sub == -1)
  {
    printf("String %s is not substring of %s.", str2, str1);
  }

  else
  {
    printf("String %s is  substring of string %s .", str2, str1);
    printf("\nSubstring %s found at location :%d", str2, sub + 1);
  }

}