大数减法运算

#include <stdio.h>         
#include <string.h> 
int compare(int*,int*);  
void swap(int* ,int* );
void deal(int*,int*,int,int);
        
int main()
{
char s1[100],s2[100];
int oper1[100]={0},oper2[100]={0},m,n,c,k,i;
gets(s1);
gets(s2);
m=strlen(s1);
n=strlen(s2);
(m<n? k=n : k=m); c=k;
for(i=0;i<m;i++)
oper1[k--]=s1[m-1-i]-'0';
for(k=c,i=0;i<n;i++)
oper2[k--]=s2[n-1-i]-'0';
if(compare(oper1,oper2)==3)  puts("0");
if(compare(oper1,oper2)==1)deal(oper1,oper2,c,k);
if(compare(oper1,oper2)==2)
{
swap(oper1,oper2);
printf("-");
deal(oper1,oper2,c,k);
}
}
void deal(int* oper1,int* oper2,int c,int k)
{
for(int i=c;i>=0;i--)
{
oper1[i]-=oper2[i];
if(oper1[i]<0)
{
oper1[i]+=10;
oper1[i-1]--;
}
}
for(int i=0;i<c;i++)
if(oper1[i]==0&&oper1[i+1])k=i+1;
for(int i=k;i<=c;i++)
printf("%d",oper1[i]);
}
void swap(int* oper1,int* oper2)
{
for(int i=0;i<100;i++)
{oper1[i]=oper1[i]+oper2[i];
oper2[i]=oper1[i]-oper2[i];
oper1[i]=oper1[i]-oper2[i];
}
} 
int compare(int* oper1,int* oper2)
{
for(int i=0;i<100;i++)
{
if(oper1[i]>oper2[i]) return 1;//操作数oper1大 
if(oper1[i]<oper2[i]) return 2;//操作数oper2大
}
return 3;//操作数oper1和操作数oper2一样大 
}