C++ 字符串字母大小写转换

C++ 字符串字母大小写转换 使用algorithm,里面的tolower(转小写)toupper(转大写)

#include <iostream>
#include <string>
using namespace std;
#include <algorithm>
 
int main()
{
    // 字符串大写字母转小写
    string up_name = "ZHANG SAN";
    string to_low_name;
    transform(up_name.begin(), up_name.end(), back_inserter(to_low_name), ::tolower);
    cout << to_low_name << endl;
 
    // 字符串小写字母转大写
    string low_name = "zhang san";
    string to_up_name;
    transform(low_name.begin(), low_name.end(), back_inserter(to_up_name), ::toupper);
    cout << to_up_name << endl;
 
    return 0;
}