程序代码：

/* Note:Your choice is C IDE */
#include <stdio.h>
void main()
{FILE *p;
    char c;
   

    if((p=fopen("abc.txt","a+"))==NULL)    

        {printf("无法打开文件");
        exit  (0) ;}
       

    fscanf(p,"%c",&c);
    printf("%d",c);        

    c=c+32;
    

    fprintf(p,"%c",c);          

   

   

} 

[此贴子已经被作者于2017-2-26 20:25编辑过]