I don't even know why I uploaded this.

C:

#include <stdio.h>
int main() {
 printf("Hello, world!");
 return 0;
}

C++:

#include <iostream>
int main() {
 std::cout << "Hello, world!";
 return 0;
}

C#:

using System;
class HelloWorld {
 static void Main() {
 Console.WriteLine("Hello, world!");
 }
}