A23114.大小写互换 本题第一篇题解

#include <bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin >> s;
    for(int i = 0;i < s.size();i++){
        if(s[i] >= 'A' and s[i] <= 'Z'){
            s[i] += 32;
        }else if(s[i] >= 'a' and s[i] <= 'z'){
            s[i] -= 32;
        }
    }
    cout << s;
    return 0;
}