Shorthand If in If-Else Construct

Let's say, for example, we want to know if the variable $test is equal to true. In this case, the if construct can be written like this:

php<?php
  $test = true;
  
  if ($test == true) {
    echo '+++';
  } else {
    echo '---';
  }
?>

When programming, such checks are required very often, so there is a more elegant shorthand form for them: instead of if ($test == true) you can simply write if ($test).

Let's rewrite our code in the shorthand form:

php<?php
  $test = true;
  
  if ($test) { // equivalent to if ($test == true)
    echo '+++';
  } else {
    echo '---';
  }
?>

Now suppose we are checking that the variable $test is not equal to true:

php<?php
  $test = true;
  
  if ($test != true) {
    echo '+++';
  } else {
    echo '---';
  }
?>

In this case, the shorthand syntax will look like this:

php<?php
  $test = true;
  
  if (!$test) { // use logical NOT
    echo '+++';
  } else {
    echo '---';
  }
?>

A similar shorthand exists for checking for false. Suppose we have the following code:

php<?php
  $test = true;
  
  if ($test == false) {
    echo '+++';
  } else {
    echo '---';
  }
?>

The condition $test == false is actually the same as $test != true:

php<?php
  $test = true;
  
  if ($test != true) { // equivalent to if ($test == false)
    echo '+++';
  } else {
    echo '---';
  }
?>

Well, we already learned how to shorten such a condition in the previous example. Let's shorten it:

php<?php
  $test = true;
  
  if (!$test) {
    echo '+++';
  } else {
    echo '---';
  }
?>

php<?php
  $test = true;
  
  if ($test == true) {
    echo '+++';
  } else {
    echo '---';
  }
?>

php<?php
  $test = true;
  
  if ($test == false) {
    echo '+++';
  } else {
    echo '---';
  }
?>

php<?php
  $test = true;
  
  if ($test != true) {
    echo '+++';
  } else {
    echo '---';
  }
?>

php<?php
  $test = true;
  
  if ($test != false) {
    echo '+++';
  } else {
    echo '---';
  }
?>