字符串中大小写字符的相互转换

Question

 

Answer 1

核心思路 ch-=32

#include <iostream>
#include <string>
//#define swap(a,b) 
using namespace std;
 
int main()
{
    string a;
 
    getline(cin,a);
    for(size_t i=0;i!=a.size();++i){
        if(isupper(a[i])){
            a[i]=tolower(a[i]);
            continue;//是大写,转成小写,循环继续.
            //不能跟着下面去,不然,又会被转大写
        }
        if(islower(a[i])){ //是小写,转成大写,继续
            a[i]=toupper(a[i]);
            continue;
        }
    }
    cout<<a<<endl;
 
    return 0;
}