Web Applications in PHP

Operators

Arithmetic operators

operator description example result
+ addition $x + $y sum of $x and $y
- subtraction $x - $y difference of $x and $y
* multiplication $x * $y product of $x and $y
/ division $x / $y quotient of $x and $y
% modulus $x % $y remainder of $x divided by $y
** power $x ** $y $x to the power $y
  • Open course/arithmetic_operators.php

 
 
 
 
 
 



 
 
 
 
 
 
 
 


<div class="margin-3">
    <?php
    $x = 10; // Assignment operator
    $y = 3; // Assignment operator
    echo "<p> \$x = $x </p>\n";
    echo "<p> \$y = $y </p>\n";
    ?>
</div>

<div class="margin-3">
    <?php
    echo "<p> \$x + \$y = $x + $y = " . ($x + $y) . "</p>\n";
    echo "<p> \$x - \$y = $x - $y = " . ($x - $y) . "</p>\n";
    echo "<p> \$x * \$y = $x * $y = " . ($x * $y) . "</p>\n";
    echo "<p> \$x / \$y = $x / $y = " . ($x / $y) . "</p>\n";
    echo "<p> \$x % \$y = $x % $y = " . ($x % $y) . "</p>\n";
    echo "<p> \$x ** \$y = $x ** $y = " . ($x ** $y) . "</p>\n";
    ?>
</div>
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Arithmetic operators

REMARKS

  • If you escape the dollar sign in a double-quoted (or heredoc) string, the corresponding variable won't be interpolated: echo "<p> \$x = $x </p>"; results in $x = 10 as output
  • You can't (easily) include arithmetic operations in a double quoted string. Therefore, we resort to string concatenation in the statement echo "<p> \$x + \$y = $x + $y = " . ($x + $y) . "</p>\n";. You should also enclose the calculation ($x + $y) with round brackets to get an error-free statement.
    • As an alternative, you could use an additional variable $sum = $x + $y, after which you can write echo "<p> \$x + \$y = $x + $y = $sum </p>\n";

Assignment operators

operator description example result
= assign $x = $y
+= add and assign $x += $y $x = $x + $y
-= subtract and assign $x -= $y $x = $x - $y
*= multiply and assign $x *= $y $x = $x * $y
/= divide and assign quotient $x /= $y $x = $x / $y
%= divide and assign modulus $x %= $y $x = $x % $y
.= concatenate and assign $x .= $y $x = $x . $y
++ increment and assign $x++ $x = $x + 1
-- decrement and assign $x-- $x = $x - 1
  • Open course/assignment_operators.php

 
 
 
 
 
 
 
 



 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 



 
 
 
 
 
 



 
 
 
 
 


<div class="margin-3">
    <?php
    $x = 10;
    $y = 2;
    $z = 3;
    echo "<p> \$x = $x </p>\n";
    echo "<p> \$y = $y </p>\n";
    echo "<p> \$z = $z </p>\n";
    ?>
</div>

<div class="margin-3">
    <?php
    echo "<blockquote>Execute the statement <code>\$x += \$y; <span class='text-lightgray'>// \$x = \$x + \$y = $x + $y</span></code></blockquote>\n";
    $x += $y;
    echo "<p> \$x = $x </p>\n";

    echo "<blockquote>Execute the statement <code>\$x -= \$z; <span class='text-lightgray'>// \$x = \$x - \$z = $x - $z</span></code></blockquote>\n";
    $x -= $z;
    echo "<p> \$x = $x  </p>\n";

    echo "<blockquote>Execute the statement <code>\$x *= \$z; <span class='text-lightgray'>// \$x = \$x * \$z = $x * $z</span></code></blockquote>\n";
    $x *= $z;
    echo "<p> \$x = $x </p>\n";

    echo "<blockquote>Execute the statement <code>\$x /= \$z; <span class='text-lightgray'>// \$x = \$x / \$z = $x / $z</span></code></blockquote>\n";
    $x /= $z;
    echo "<p> \$x = $x </p>\n";

    echo "<blockquote>Execute the statement <code>\$x %= \$y; <span class='text-lightgray'>// \$x = \$x % \$y = $x % $y</span></code></blockquote>\n";
    $x %= $y;
    echo "<p> \$x = $x </p>\n";

    echo "<blockquote>Execute the statement <code>\$y++; <span class='text-lightgray'>// \$y = \$y + 1 = $y + 1</span></code></blockquote>\n";
    $y++;
    echo "<p> \$y = $y </p>\n";

    echo "<blockquote>Execute the statement <code>\$z--; <span class='text-lightgray'>// \$z = \$z - 1 = $z - 1</span></code></blockquote>\n";
    $z--;
    echo "<p> \$z = $z </p>\n";
    ?>
</div>
<hr>
<div class="margin-3">
    <?php
    $name = 'John';
    $surname = 'Doe';
    echo "<p> \$name = '$name' </p>\n";
    echo "<p> \$surname = '$surname' </p>\n";
    ?>
</div>

<div class="margin-3">
    <?php
    echo "<blockquote>Execute the statement <code>\$name .= \$surname; <span class='text-lightgray'>// \$name = \$name . \$surname = '$name' . '$surname'</span></code></blockquote>\n";
    $name .= $surname;
    echo "<p> \$name = '$name' </p>\n";
    ?>
</div>
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Assignment operators

Comparison operators

operator description example result
== equal $x == $y true if $x is equal to $y
=== identical $x === $y true if $x is equal to $y and they are of the same type
!=
<>		 not equal $x != $y
$x <> $y		 true if $x is not equal to $y
!== not identical $x !== $y true if $x is not equal to $y or they are not of the same type
< less than $x < $y true if $x is less than $y
<= less than or equal to $x <= $y true if $x is less than or equal to $y
> greater than $x > $y true if $x is greater than $y
>= greater than or equal to $x >= $y true if $x is greater than or equal to $y
  • Open course/comparison_operators.php

 
 
 
 
 
 
 
 



 
 
 
 
 
 
 
 
 


<div class="margin-3">
    <?php
    $x1 = 10;
    $x2 = '10';
    $y = 5;
    echo "<p> \$x1 = $x1 </p>\n";
    echo "<p> \$x2 = '$x2' </p>\n";
    echo "<p> \$y = $y </p>\n";
    ?>
</div>

<div class="margin-3">
    <?php
    echo "<p> (\$x1 == \$x2) = ($x1 == '$x2') = " . ($x1 == $x2) . "</p>\n";
    echo "<p> (\$x1 === \$x2) = ($x1 === '$x2') = " . ($x1 === $x2) . "</p>\n";
    echo "<p> (\$x1 != \$y) = ($x1 != $y) = " . ($x1 != $y) . "</p>\n";
    echo "<p> (\$x2 <> \$y) = ('$x2' <> $y) = " . ($x2 <> $y) . "</p>\n";
    echo "<p> (\$x1 < \$y) = ($x1 < $y) = " . ($x1 < $y) . "</p>\n";
    echo "<p> (\$x1 > \$y) = ($x1 > $y) = " . ($x1 > $y) . "</p>\n";
    echo "<p> (\$x2 > \$y) = ('$x2' > $y) = " . ($x2 > $y) . "</p>\n";
    ?>
</div>
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Comparison operators

REMARK

Notice that true is depicted as 1, while false corresponds to an empty string

Logical operators

operator example result
and
&&		 $x and $y
$x && $y		 true if both $x and $y are true
or
||		 $x or $y
$x || $y		 true if either $x or $y is true
xor $x xor $y true if either $x or $y is true, but not both
! !$x true if $x is false (not true)
  • Open course/logical_operators.php

 
 
 
 
 
 



 
 
 
 
 
 
 
 
 


<div class="margin-3">
    <?php
    $x = 6;
    $y = 4;
    echo "<p> \$x = $x </p>\n";
    echo "<p> \$y = $y </p>\n";
    ?>
</div>

<div class="margin-3">
    <?php
    echo "<p> (\$x < 8 and \$y > 3) = ($x < 8 and $y > 3) = " . ($x < 8 and $y > 3) . "</p>\n";
    echo "<p> (\$x < 8 && \$y > 6) = ($x < 8 && $y > 6) = " . ($x < 8 && $y > 6) . "</p>\n";
    echo "<p> (\$x < 8 or \$y > 3) = ($x < 8 or $y > 3) = " . ($x < 8 or $y > 3) . "</p>\n";
    echo "<p> (\$x < 8 || \$y > 6) = ($x < 8 || $y > 6) = " . ($x < 8 || $y > 6) . "</p>\n";
    echo "<p> (\$x < 8 xor \$y > 3) = ($x < 8 xor $y > 3) = " . ($x < 8 xor $y > 3) . "</p>\n";
    echo "<p> (\$x < 8 xor \$y > 6) = ($x < 8 xor $y > 6) = " . ($x < 8 xor $y > 6) . "</p>\n";
    echo "<p> !(\$x == \$y) = !($x == $y) = " . !($x == $y) . "</p>\n";
    ?>
</div>
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Logical operators

Last Updated: 9/17/2021, 2:08:35 PM

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