#include<stdio.h>
#include<stdlib.h>
int main()
{
    char c[7];
    int i=0,a;
    FILE*fp;
    if ((fp = fopen("sc.dat", "w")) == NULL);
    {
        printf("error\n");
        exit(0);
    }
    printf("输入一些字符:\n");
    while ((a = getchar()) != '\n')
        c[i++] = a;
    for (i = 0; i < 7; i++)
    {
        if (c[i] >= 'a'&&c[i] <= 'z')
            c[i] = c[i] - 32;
    }
    for (i = 0; c[i] != '!'; i++)
    {
        fputc(c[i], fp);
        printf("%c", c[i]);
    }
    printf("\n");
    fclose(fp);
    return 0;
}

多打了个分号

if 条件语句后面多一个;