Question

In C: Find a string within a string Given two strings S1 & S2, search for an occurrence of the second string within a first string. Note: Do not use system library for the implementation. Input: Code Zinger University Zinger where, First line represents string S1. Second line represents string S2. Output: 5 Here 'Zinger' word starts at 5th index within 'Code Zinger University’. Assume that, The length of strings S1 & S2 are within the range [1 to 10000]. Character comparisons will be case-sensitive.

Answer 1

If you have any doubts, please give me comment...

#include <stdio.h>

#define MAX_SIZE 10000

int findSubstrIndex(char S1[], char S2[]);

int main()

{

    char S1[MAX_SIZE], S2[MAX_SIZE];

    int index;

    printf("Enter String1: ");

    scanf("%[^\n]s", S1);

    printf("Enter String2: ");

    scanf("\n%[^\n]s", S2);

    index = findSubstrIndex(S1, S2);

    if (index == -1)

        printf("%s not found!\n", S2);

    else

        printf("%s found at index %d\n", S2, index);

    return 0;

}

int findSubstrIndex(char S1[], char S2[])

{

    int i = 0, j;

    while (S1[i] != '\0')

    {

        if (S1[i] == S2[0])

        {

            int exists = 1;

            j = 1;

            while (S2[j] != '\0')

            {

                if (S2[j] != S1[i + j])

                {

                    exists = 0;

                    break;

                }

                j++;

            }

            if (exists){

                return i;

            }

        }

        i++;

    }

    return -1;

}