I'm trying to do this exercise for my exam tomorrow.

I need to compare a string of my own input and see if that string is appearing on the file. This needs to be done directly on the file, so I cannot extract the string to my program and compare them "indirectly".

I found this way but I'm not getting it right, and I don't know why. The algorithm sounds good to me.

Any help, please? I really need to focus on this one.

Thanks in advance, guys.

#include<stdio.h>

void comp();

int main(void)
{
    comp();

    return 0;
}

void comp()
{
    FILE *file = fopen("e1.txt", "r+");

    if(!file)
    {
        printf("Not possible to open the file");
        return;
    }

    char src[50], ch;
    short i, len;

    fprintf(stdout, "What are you looking for? \nwrite: ");
    fgets(src, 200, stdin);

    len = strlen(src);


    while((ch = fgetc(file)) != EOF)
    {
        i = 0;

        while(ch == src[i])
        {
            if(i <= len)
            {
                printf("%c - %c", ch, src[i]);
                fseek(file, 0, SEEK_CUR + 1);
                i++;

            }
            else break;
        }
    }
}