大数加法

#include<iostream>
#include<string>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
#define CLR(arr, val) memset(arr, val, sizeof(arr))
#define MAX 1010
int a[MAX], b[MAX];

int main()
{
	//freopen("Input.txt", "r", stdin);
	int N, len1, len2, i, k, up, tmp, ncase = 1;
	string str1, str2;
	scanf("%d", &N);
	while(N--)
	{
		CLR(a, 0); CLR(b, 0);
		cin>>str1>>str2;
		len1 = str1.length(); len2 = str2.length();
		for(i = len1 - 1, k = 0; i >= 0; --i)
			a[k++] = str1[i] - '0';
		for(i = len2 - 1, k = 0; i >= 0; --i)
			b[k++] = str2[i] - '0';
		for(i = 0, up = 0; i < MAX; ++i)
		{
			a[i] = a[i] + b[i] + up;
			up = a[i] / 10;
			a[i] %= 10;		
		}
		for(i = MAX -1; i >= 0; --i)
			if(a[i]) break;
		printf("Case %d:\n", ncase++);
		cout<<str1<<" + "<<str2<<" = ";
		for(k = i; k >= 0; --k)
			printf("%d", a[k]);
		printf("\n");
	}
	return 0;
}