Functions for character-case conversions in C + +

First Judge

If it is lowercase:

if (Islower (Str[i]))

The lowercase letter becomes the capital letter, the function is ToUpper
Str[i] = ToUpper (Str[i]);
Else

If it is an uppercase letter. The lowercase letter function is: ToLower
Str[i] = ToLower (Str[i]);

The detection capital letter is:isupper

The detection lowercase letter is: islower

Uppercase-------> Lowercase: ToLower

lowercase--------> Uppercase: ToUpper

Example

Code:

#include <iostream>
#include <cstdio>
#include <cstring>
#define MAXN 21
using namespace Std;
Char STR[MAXN];
int main ()
{
cin>>str;
for (int i = 0; i < strlen (str); i++)
{
if (Islower (Str[i]))
Str[i] = ToUpper (Str[i]);
else if (Isupper (Str[i]))
Str[i] = ToLower (Str[i]);
}
cout<<str;
return 0;
}

Functions for character-case conversions in C + +