PHP - Operator Assignment operators

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Introduction

Here is how the basic assignment operator ( = ) can be used to assign a value to a variable: 

$test_var = 1.23;

The preceding expression itself evaluates to the value of the assignment: 1.23.

This is because the assignment operator produces a value as well as carrying out the assignment operation.

You can write code such as: 

$another_var = $test_var = 1.23;

Both $test_var and $another_var now contain the value 1.23

The equals sign = can be combined with other operators to give you a combined assignment operator.

The combined assignment operators, such as +=, -=, give you a shorthand method for performing typical arithmetic operations.

For example, you can write: 

$first_number += $second_number;

rather than: 

$first_number = $first_number + $second_number;

This works for other kinds of operators.

For example, the concatenation operator can be combined with the equals sign as .= 

$a = "a";
$b = "b";
$a .= $b;                 // $a now contains  "ab"

The assignment operator assigns the result of an expression to a variable.

An expression can be as simple as a number, or, the result of a series of arithmetic operations.

The following example assigns the result of an expression to a variable:

Demo

<?php
    $a = 3 + 4 + 5 - 2; //from  w  ww . ja  v a 2s.  com
    var_dump($a); // 10 
?>

Result

You can build them combining an arithmetic operator and the assignment operator.

Demo

<?php
    $a = 13; //from   ww w .  ja v a 2 s . c  o m
    $a += 14; // same as $a = $a + 14; 
    var_dump($a); 
    $a -= 2; // same as $a = $a - 2; 
    var_dump($a); 
    $a *= 4; // same as $a = $a * 4; 
    var_dump($a);
?>

Result