PHP Assignment Operators

Summary: in this tutorial, you will learn about the most commonly used PHP assignment operators.

Introduction to the PHP assignment operator

PHP uses the = to represent the assignment operator. The following shows the syntax of the assignment operator:

$variable_name = expression;
Code language: PHP (php)

On the left side of the assignment operator (=) is a variable to which you want to assign a value. And on the right side of the assignment operator (=) is a value or an expression.

When evaluating the assignment operator (=), PHP evaluates the expression on the right side first and assigns the result to the variable on the left side. For example:

$x = 10; $y = 20; $total = $x + $y;
Code language: PHP (php)

In this example, we assigned 10 to $x, 20 to $y, and the sum of $x and $y to $total.

The assignment expression returns a value assigned, which is the result of the expression in this case:

$variable_name = expression;
Code language: PHP (php)

It means that you can use multiple assignment operators in a single statement like this:

$x = $y = 20;
Code language: PHP (php)

In this case, PHP evaluates the right-most expression first:

$y = 20
Code language: PHP (php)

The variable $y is 20.

The assignment expression $y = 20 returns 20 so PHP assigns 20 to $x. After the assignments, both $x and $y equal 20.

Arithmetic assignment operators

Sometimes, you want to increase a variable by a specific value. For example:

$counter = 1; $counter = $counter + 1;
Code language: PHP (php)

How it works.

  • First, $counter is set to 1.
  • Then, increase the $counter by 1 and assign the result to the $counter.

After the assignments, the value of $counter is 2.

PHP provides the arithmetic assignment operator += that can do the same but with a shorter code. For example:

$counter = 1; $counter += 1;
Code language: PHP (php)

The expression $counter += 1 is equivalent to the expression $counter = $counter + 1.

Besides the += operator, PHP provides other arithmetic assignment operators. The following table illustrates all the arithmetic assignment operators:

OperatorExampleEquivalentOperation
+=$x += $y$x = $x + $yAddition
-=$x -= $y$x = $x – $ySubtraction
*=$x *= $y$x = $x * $yMultiplication
/=$x /= $y$x = $x / $yDivision
%=$x %= $y$x = $x % $yModulus
**=$z **= $y$x = $x ** $yExponentiation

Concatenation assignment operator

PHP uses the concatenation operator (.) to concatenate two strings. For example:

<?php $greeting = 'Hello '; $name = 'John'; $greeting = $greeting . $name; echo $greeting;
Code language: HTML, XML (xml)

Output:

Hello John

By using the concatenation assignment operator you can concatenate two strings and assigns the result string to a variable. For example:

<?php $greeting = 'Hello '; $name = 'John'; $greeting .= $name; echo $greeting;
Code language: HTML, XML (xml)

Summary

  • Use PHP assignment operator (=) to assign a value to a variable. The assignment expression returns the value assigned.
  • Use arithmetic assignment operators to carry arithmetic operations and assign at the same time.
  • Use concatenation assignment operator (.=)to concatenate strings and assign the result to a variable in a single statement.
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