Операторы в PHP

   <?
    $firstVariable = 5;
    $secondVariable = 10 - $firstVariable + 2;
    echo $secondVariable.'<br>';
   
    $firstVariable = 20;
    $secondVariable = $firstVariable / 4 * 2;
    echo $secondVariable.'<br>';
   
    $firstVariable = 60;
    $secondVariable = -$firstVariable;
    echo $secondVariable.'<br>';
   
    $firstVariable = 20;
    $secondVariable = $firstVariable % 3;
    echo $secondVariable.'<br>';
   
    $firstVariable = 2;
    $secondVariable = $firstVariable ** 3;
    echo $secondVariable.'<br>';
   
    $firstVariable = 10;
    $firstVariable--;
    ++$firstVariable;
    echo $firstVariable.'<br>';
   
    $firstVariable = 10;
    $firstVariable += 3;
    echo $firstVariable.'<br>';
   
    $firstVariable = 'First';
    $firstVariable .= 'Second';
    echo $firstVariable.'<br>';
   
    $firstVariable = 'One';
    $secondVariable = 'Two';
    $thirdVariable = $firstVariable.$secondVariable;
    echo $thirdVariable.'<br>';
   
    $firstVariable = 'abcde';
    echo $firstVariable[4];
    echo '<br>';
   
    $firstVariable = 1;
    $secondVariable = '1';
    if($firstVariable == $secondVariable) echo 'Равны';
    echo '<br>';
   
    $firstVariable = 1;
    $secondVariable = 1;
    if($firstVariable === $secondVariable) echo 'Равны';
    echo '<br>';
   
    $firstVariable = 1;
    $secondVariable = 2;
    if($firstVariable != $secondVariable) echo 'Не равны';
    echo '<br>';
   
    $firstVariable = 1;
    $secondVariable = 2;
    if($firstVariable <= $secondVariable) echo 'Меньше';
    echo '<br>';
   ?>