打开文件“fill.dat”并将文件中的内容输出到屏幕
FILE*p = fopen("fill.dat", "rb"); 主要看文件内容，是不是结构体，如果是结构体，要先定义结构体，再读取。 参考：
<span class="hljs-comment">/*成绩输出*/</span>
void output()
{
int i;
char c;
<span class="hljs-type">FILE</span> <span class="hljs-operator">*</span> fp; <span class="hljs-comment">//定义一个文件指针fp</span>
fp <span class="hljs-operator">=</span> fopen(<span class="hljs-string">"students.txt"</span>, <span class="hljs-string">"rt"</span>); <span class="hljs-comment">//以"读取的" 方式打开students文本文件</span>
system(<span class="hljs-string">"cls"</span>); <span class="hljs-comment">//清屏//</span>
getchar();
printf(<span class="hljs-string">"|#学号<span class="hljs-subst">\t</span>姓名<span class="hljs-subst">\t</span>语文<span class="hljs-subst">\t</span>数学<span class="hljs-subst">\t</span>英语<span class="hljs-subst">\t</span>总成绩<span class="hljs-subst">\t</span>平均分<span class="hljs-subst">\t</span>#|<span class="hljs-subst">\n</span>"</span>);
<span class="hljs-keyword">do</span> {
<span class="hljs-keyword">for</span> (i <span class="hljs-operator">=</span> <span class="hljs-number">0</span>; i <span class="hljs-operator"><</span> n; i<span class="hljs-operator">++</span>)
{
fread(<span class="hljs-operator">&</span>student[i], sizeof(<span class="hljs-keyword">struct</span> students), <span class="hljs-number">1</span>, fp);
printf(<span class="hljs-string">" %d "</span>, student[i].num);
printf(<span class="hljs-string">" %s "</span>, student[i].name);
printf(<span class="hljs-string">" %d "</span>, student[i].chinese);
printf(<span class="hljs-string">" %d "</span>, student[i].math);
printf(<span class="hljs-string">" %d "</span>, student[i].english);
printf(<span class="hljs-string">" %d "</span>, student[i].sum);
printf(<span class="hljs-string">" %d <span class="hljs-subst">\n</span>"</span>, student[i].ave);
}
printf(<span class="hljs-string">"<span class="hljs-subst">\n</span><span class="hljs-subst">\n</span><span class="hljs-subst">\t</span><span class="hljs-subst">\t</span><span class="hljs-subst">\t</span><span class="hljs-subst">\t</span>是否继续其它操作(Y/N):"</span>); <span class="hljs-comment">//提示是否继续</span>
scanf(<span class="hljs-string">"%c"</span>, <span class="hljs-operator">&</span>c);
c <span class="hljs-operator">=</span> getchar();
} <span class="hljs-keyword">while</span> ( c <span class="hljs-operator">==</span> 'y' <span class="hljs-operator">||</span> c <span class="hljs-operator">==</span> '<span class="hljs-type">Y</span>');
fclose(fp); <span class="hljs-comment">//关闭文件//</span>
}