Marked Demo

bash

#!/bin/bash

if [ $a  -eq  true ]
then
echo "A 'a'"
else
echo "B 'b'"
fi

function foo(a) {
local a = 0
count = a + 1
echo count
return
}

# comment

: <<COMMENT
comment line a
true comment line b
COMMENT

: <<x
comment line a
true comment line b
x

: '
comment line a
true comment line b
'

bash (scroll example)

#!/bin/bash

if [ $a  -eq  true ]
then
echo "A 'a'"
else
echo "B 'b'"
fi

#example to showcase the horizontal scroll with the numbers fading over the code.

c

#include <stdio.h>
#include "library.h"

#ifndef EXTENDED
/* defined */
#else
/* undefined */
#endif

int foo(int a) {
int count;
int quo;

a = 0;
count = a + 1;

if (a == 1) {
  printf("A 'a'");
} else {
  printf('B "b"');
}
return count;
}

// comment

/* comment line a
true comment line b
*/

cpp

#include <iostream>
#include "library.h"

using namespace std;

#ifndef EXTENDED
/* defined */
#else
/* undefined */
#endif

int foo(int a) {
int a = 0;
int count = a + 1;
if (a == true) {
  cout << "A 'a'" << endl;
} else {
  cout << 'B "b"'<< endl;
}
string quo = R"(
  quote line a
  quote line b
)";
return count;
}

// comment that extends to the edge of the box without wordwrap

/* comment line a
true comment line b 
*/

cs

#include "library.h"
#include <header name>

#ifndef EXTENDED
/* defined */
#else
/* undefined */
#endif

void foo(int a) {
a = 0;
count = a + 1
if ( a == true ) {
  Console.WriteLine( "A 'a'" );
} else {
  Console.WriteLine( "B 'b'" );
}
return count; 
}

// comment

/* comment line a
true comment line b
*/

fs

let addTuple aTuple =
let (x,y) = aTuple
x + y

let foo a =
let a = 0;
let count = a + 1
if a == true then printfn "A 'a'";
else printfn "B 'b'";

// comment

/* comment line a
true comment line b
*/

go

package main
import "fmt"

func main() {
var a = 0
var b = true
count := a + 1
if b == true {
  fmt.Println("A 'a'")
} else {
  fmt.Println(`B "b"`)
}

var quo = `
  quote line a
  quote line b
`
concatenated := fmt.Sprintf("%d%s", count, quo)
fmt.Println(concatenated)
}

// comment

/* comment line a
true comment line b 
*/

html

<!DOCTYPE html>
<html>
<body>
  <!-- <!DOCTYPE html> 
  -->
  <!--h1>foo</h1-->
  <h1>My First Heading</h1>
  <p class='test'>My first paragraph.</p>
  <a href="https://www.w3schools.com">
      This is a link
  </a> 
  </body>
</html>

java

import library.*;

public class Main {
  public static void main(String[] args) {
      int foo(int a) {
          int a = 0;
          int count = a + 1;
          if (a == true) {
              System.out.println("A 'a'");
          } else {
              System.out.println("B 'b'");
          }
          String quo = "quote line a\n" +
                  "quote line b";

          // Java 13 Text Blocks
          String quo = """quote line
                  quote line b""";

          return count;
      }
  }
}

// comment

/* comment line a
true comment line b 
*/

javascript

import * from "library.js";
import { library } from "library.js";

function foo(a){
  var a = 0;
  var count = a + 1;
  if ( a == true ) {
    console.log( "A 'a'" );
  } else {
    console.log( `B "b"` );
  }
  var quo = `
    quote line a
    quote line b
  `;
  return count; 
};

// comment

/* comment line a
true comment line b 
*/

export { foo };

kotlin

package main
import library as library;

fun foo(a: Int): Int {
  var a = 0
  var count = a + 1
  if (a == true) {
      println("A 'a'")
  } else {
      println("B 'b'")
  }
  val quo = """
      quote line a
      quote line b
  """.trimIndent()
  return count
}

// comment

/* comment line a
true comment line b 
*/

matlab

library = importdata('library.js');

function count = foo(a)
  a = 0;
  count = a + 1;
  if (a == true)
      disp('A "a"');
  else
      disp('B "b"');
  end
  quo = sprintf('quote line a');
  return count;
end

%comment

%{ comment
comment line a
true comment line b
%}

perl

sub foo {
my ($a) = @_;

my $a = 0;
my $count = $a + 1;

if ($a == True) { 
  print "A 'a'";
} else {
  print 'B "b"';
}

my $quo = <<END;
  quote line a
  quote line b
END

return $count;
}

#comment

=pod
comment line a
True comment line b
=cut

python

from library.js import *
from library.js import library

def foo(a):
  a = 0
  count = a + 1
  if a == True:
      print("A 'a'")
  else:
      print('B "b"')

  quo = """
  quote line a
  quote line b
  """
  return count

# comment

"""
comment line a
True comment line b
"""

'''
comment line a
True comment line b
'''

r

source("library.js")

foo <- function(a) {
a <- 0
count <- a + 1
if (a == TRUE) {
  cat("A 'a'")
} else {
  cat('B "b"')
}
quo <- c(
  "quote line a",
  "quote line b"
)
return(count)
}

# comment

vb


'comment'

System.Console.WriteLine("Log text")

Dim UserName As String = "MyUserName"