大数相加 a+b

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<ctype.h>
#include<math.h>
#define N 1010

char s1[N], s2[N];
int a[N], b[N], c[N];

int main()
{
    int T, len1, len2, i, k, cnt=1;
    scanf("%d", &T);
    getchar();

    while(T--)
    {
        scanf("%s %s", s1, s2);
        getchar();

        len1=strlen(s1);
        len2=strlen(s2);
        memset(a, 0, sizeof(a));
        memset(b, 0, sizeof(b));
        memset(c, 0, sizeof(c));
        k=0;
        for(i=len1-1; i>=0; i--)
            a[k++]=s1[i]-'0';
        k=0;
        for(i=len2-1; i>=0; i--)
            b[k++]=s2[i]-'0';
        for(i=0; i<len1 && i<len2; i++)
        {
            if(a[i]+b[i]+c[i]>9)
            {
                c[i]=(a[i]+b[i]+c[i])%10;
                c[i+1]=1;
            }
            else
            {
                c[i]=a[i]+b[i]+c[i];
            }
        }
        while(i<len1)
        {
            if(c[i]+a[i]>9)
            {
                c[i]=(c[i]+a[i])%10;
                c[i+1]=1;
            }
            else
            {
                c[i]=c[i]+a[i];
            }
            i++;
        }
        while(i<len2)
        {
            if(c[i]+b[i]>9)
            {
                c[i]=(c[i]+b[i])%10;
                c[i+1]=1;
            }
            else
            {
                c[i]=c[i]+b[i];
            }
            i++;
        }

        i=N-1;
        while(!c[i]) i--;

        if(cnt>1)
            printf("\n");

        printf("Case %d:\n", cnt++);
        printf("%s + %s = ", s1, s2);

        for(; i>=0; i--)
            printf("%d", c[i]);
        printf("\n");
    }
    return 0;
}