#include<iostream>using namespace std;int main(){ int T ; cin>>T;string a[20],b[20],sum[20]; for(int i=1;i<=T;i++) { cin>>a[i]>>b[i]; sum[i]=a[i]+b[i]; } for (i=1;i<=T;i++) { cout<<"Case "<<i<<endl; cout<<a[i]<<"+"<<b[i]<<"="<<sum[i]; cout<<endl; } return 0;}用字符串怎么相加啊?