大小寫轉換

小轉大

toupper(字元)
回傳ASCII

#include <bits/stdc++.h>
using namespace std;

signed main(){
    cout<<char(toupper('a'));
    cout<<"\n";
    cout<<char('a'-32);
}

A
A

大轉小

tolower(字元)
回傳ASCII

#include <bits/stdc++.h>
using namespace std;

signed main(){
    cout<<char(tolower('A'));
    cout<<"\n";
    cout<<char('A'+32);
}

a
a