在文件中输入字符串HelloWord

#include<stdio.h>
#include<string.h>
#include <stdlib.h>
extern void solve();
int main(void)//主函数题目已写好
{
    solve();
    FILE *f = fopen("in.txt","r");
    char s[100];
    fscanf(f,"%s",&s);
    if(strcmp(s,"HelloWorld")==0)
        printf("YES");
    else
        printf("NO");
    return 0;
}
void solve(){//（以下是题目要求补充的）
    FILE *fp;
    fp=fopen("in.txt","w");
    fprintf(fp,"%s","HelloWorld");
    fclose(fp);
}