NaiveStringMatching.c

// C program for Naive Pattern Searching algorithm
#include <stdio.h>
#include <string.h>
int count=0,flag=0;
void search(char* pat, char* txt)
{
    int M = strlen(pat);
    int N = strlen(txt);
    int j;
    /* A loop to slide pat[] one by one */
    for (int i = 0; i <= N - M; i++) {
        /* For current index i, check for pattern match */
        for (j = 0; j < M; j++){
        count++;
            if (txt[i + j] != pat[j])
                break;
            }

        if (j == M){
                // if pat[0...M-1] = txt[i, i+1, ...i+M-1]
            flag=1;
            printf("Pattern found at index %d \n", i);
            break;//comment break  to find all instances of pattern.
        }
    }
}
/* Driver program to test above function */
int main()
{
    char txt[100];
    char pat[100];
    printf("ENTER TEXT\n");
	scanf("%[^\n]s",txt);//text in which to be searched
	getchar();
	printf("ENTER PATTERN\n");
	scanf("%[^\n]s",pat);//pattern to be searched
    search(pat, txt);
    if(flag==0)
    {
        printf("Pattern not found\n");
    }
    printf("THE NO OF COMPARISONS=%d\n",count);
    return 0;
}