问在C编程中使用暴力搜索，在C编程中读取.fna文件

EN

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXCHAR 70000

void search(char* pattern, char* text)
{

    int M = strlen(pattern);
    int N = strlen(text);

    for (int x = 0; x <= N - M; x++) {
        int y;

        for (y = 0; y < M; y++)
            if (text[x + y] != pattern[y])
                break;

        if (y == M)
        {
            printf("Found pattern at position %d \n", x+1);
        }
    }}

int main()
{

    FILE *fp;
    char str[MAXCHAR];
    char pattern[] = "GTTCTTT";
    char* filename = "D:\\Desktop\\NC_007409.fna";
    fp = fopen(filename, "r");

    if (fp == NULL){
        printf("Could not open file %s",filename);
        return 1;
    }

    while (fgets(str, MAXCHAR, fp) != NULL)
        search(pattern, str);
        return 0;
}