求助

[zkm11]

#include <stdio.h>
#define x 12345678
long int fff(long int m)
{
long int t,*p1,*p2;
for(i=1;i<j;i++,j--)
{
t=*p1;
*p1=*p2;
*p2=t;
}

return(m);
}
main()
{long int n;
FILE *p;
if ((p=fopen("file1.txt","w"))==NULL)
{printf("this file can not open\n");
exit(0);
}
n=fff(x);
printf("%ld\n",n);
fprintf(p,"%ld\n",n);
}

编写一个函数fff,它的功能是将任意非负整数（如5678）倒序输出(8765)
注意：部分源程序已给出，请勿改动主函数main()和已给出的源程序，仅在fff函数中的花括号内填入你编写地若干语句

[ttlb]

long int fff(long int m)
{
long n = 0;
while (m / 10 != 0)
{
n = n * 10 + m % 10;
m /= 10;
}
n = n * 10 + m;
return(n);
}