HDU 1002 A + B Problem II(大数相加)

#include<cstdio>
#include<cstring>
const int maxn=1005;
char a[maxn],b[maxn],c[maxn];
void sum()
{
int lena=strlen(a);
int lenb=strlen(b);
int i,j,cid;
int carry=0;
memset(c,'\0',sizeof(c));
for(i=lena-1,cid=1004,j=lenb-1;j>=0&&i>=0;i--,j--,cid--)
{
c[cid]=(a[i]+b[j]+carry-2*'0')%10+'0';
carry=(a[i]+b[j]+carry-2*'0')/10;
}
while(i>=0)
{
c[cid]=(a[i]+carry-'0')%10+'0';
carry=(a[i]+carry-'0')/10;
i--;
cid--;
}
while(j>=0)
{
c[cid]=(b[j]+carry-'0')%10+'0';
carry=(b[j]+carry-'0')/10;
j--;
cid--;
}
if(carry==1)
{
c[cid]=carry+'0';
}
}
int main()
{
int T;
int kase=1;
scanf("%d",&T);
while(T--)
{
scanf("%s %s",a,b);
sum();
char *ans;
int i;
for(i=0;i<1005;i++)
{
if(c[i]!='\0')
{
ans=&c[i];
break;
}
}
if(kase==1)
{
printf("Case %d:\n%s + %s = %s\n",kase++,a,b,ans);
}
else
{
printf("\nCase %d:\n%s + %s = %s\n",kase++,a,b,ans);
}
}
return 0;
}