1.java

public class helloworld {
    public static void main(String[] args) {
        System.out.println("helloworld");
    }
}

2.C

#include<stdio.h>
void main()
{
    printf("helloworld\n");
    return(0);
}

3.C++

#include <iostream>
using namespace std;
void main()                 
{
    cout << "helloworld\n";
}  

5.C Sharp(C#)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace log{
    class helloworld{
        static void  Main(string[] args){
            Console.WriteLine("helloworld!");
        }
    }
}

6.python

print("helloworld")

7.javascript

console.log("helloworld");

8.php

<?php
 echo "helloworld!\n" ;
?>

9.asp

<% response.write("helloworld") %>

10.vbscript

msgbox "helloworld"

11.pascal

begin
    writeln('helloWorld!');
end.

12.golang

package main
import "fmt"
func main(){
    fmt.Printf("helloworld\n");
}

13.prel

print "helloworld";

14.ruby

puts "helloworld"

15.R

cat('helloworld')

16.shell

#!/path
echo "helloworld"

17.html

<h1>helloworld<h1>

18.lua

print("hello world")

20.Objective-C

#import <Foundation/Foundation.h>
int main(int argc,const char *argv[])
{
    NSLog(@"Helloworld");
    return (0);
}