how to convert char to lowercase in c++ code example

Example 1: how to make a char uppercase in java

char q = Character.toUpperCase('d');

Example 2: python convert string to lowercase

# By Alan W. Smith and Petar Ivanov
s = "Kilometer"
print(s.lower())

Example 3: convert characters to lowercase c++

str[i] = tolower(str[i]);

Example 4: tolower in c++

#include <cctype>
#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

int main()
{
    char str[] = "John is from USA.";

    cout << "The lowercase version of \"" << str << "\" is " << endl;

    for (int i=0; i<strlen(str); i++)
        putchar(tolower(str[i]));
    
    return 0;
}