<?php

$welcome = 'Hello';
$world = 'World';

// Solution 1
$msg = $welcome . ', ' . $world . ' !';

// Solution 2
$msg = "$welcome, $world !";

echo $msg;

echo '<br>';

/* --- 0 && null --- */

echo '0 == null => ';

if(0 == null) {
	echo 'yes';
} else {
	echo 'no';
}

echo '<br>';

echo '0 === null => ';

if(0 === null) {
	echo 'yes';
} else {
	echo 'no';
}

/* --- ' ' && 0 --- */

echo '<br>';

echo '\' \' == 0 => ';

if(' ' == 0) {
	echo 'yes';
} else {
	echo 'no';
}

echo '<br>';

echo '\' \' === 0 => ';

if(' ' === 0) {
	echo 'yes';
} else {
	echo 'no';
}

echo '<br>';

/* --- ' ' && null --- */

echo '\' \' == null => ';

if(' ' == null) {
	echo 'yes';
} else {
	echo 'no';
}

echo '<br>';

echo '\' \' === null => ';

if(' ' === null) {
	echo 'yes';
} else {
	echo 'no';
}


?>