文件操作

#include <stdio.h>

int main( void )
{
    char answer[1*1024+1]; // 其实题目没交代答案长度
    printf( "请输入正确答案：" );
    scanf( "%s", answer );

    unsigned long long n; // 其实题目没交代n的取值范围
    printf( "请输入新生人数（N）：" );
    scanf( "%llu", &n );

    FILE* fout = fopen( "result.txt", "wt" );
    for( unsigned long long i=0; i!=n; ++i )
    {
        char filename[20+5]; // 其实题目没交代n的取值范围，所以文件名最长是多少就无法确定
        sprintf( filename, "%llu.txt", 1+i );

        char the[ sizeof answer ];
        FILE* fin = fopen( filename, "rt" );
        fscanf( fin, "%s", the );
        fclose( fin );

        size_t count = 0;
        for( size_t j=0; answer[j]!='\0' && the[j]!='\0'; ++j )
            count += answer[j]==the[j];

        fprintf( fout, "%zu\n", count*5 ); // 其实题目没交代一题几分
    }
    fclose( fout );
    puts( "结果已保存" );
}