大数加法

#include<iostream>

using namespace std;

int main()
{
    int cnt =1;
    int n;
    cin>>n;
    while(n--)
    {
        string str1,str2;
        int var[1000]={0},var1[1000]={0},var2[1000]={0};
        int len1,len2,lenm;
        cin>>str1>>str2;
        len1 = str1.size();
        len2 = str2.size();
        lenm = len1>len2 ? len1:len2;

        for(int i=len1-1,j=0;i>=0;i--)
        {
            var1[j++] = str1[i]-'0';
        }
        for(int i=len2-1,j=0;i>=0;i--)
        {
            var2[j++] = str2[i]-'0';
        }
        int ca=0;
        for(int i=0,j=0;i<lenm;i++)
        {
            var[j++] = (var1[i]+var2[i]+ca)%10;
            ca = (var1[i]+var2[i]+ca)/10;
        }
        while(ca)
        {
            var[lenm++] = ca%10;
            ca = ca/10;
        }
        cout<<"Case "<<cnt++<<":"<<endl;
        cout<<str1<<" + "<<str2 <<" = ";
        for(int i=lenm-1;i>=0;i--)
        {
            cout<<var[i];
        }
        cout<<endl;
    }
    return 0;
}