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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:

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:

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:

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

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

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:

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:

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:

Concatenation assignment operator

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

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

• 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.

• Language Reference

Assignment Operators

The basic assignment operator is "=". Your first inclination might be to think of this as "equal to". Don't. It really means that the left operand gets set to the value of the expression on the right (that is, "gets set to").

The value of an assignment expression is the value assigned. That is, the value of " $a = 3 " is 3. This allows you to do some tricky things: <?php $a = ( $b = 4 ) + 5 ; // $a is equal to 9 now, and $b has been set to 4. ?>

In addition to the basic assignment operator, there are "combined operators" for all of the binary arithmetic , array union and string operators that allow you to use a value in an expression and then set its value to the result of that expression. For example: <?php $a = 3 ; $a += 5 ; // sets $a to 8, as if we had said: $a = $a + 5; $b = "Hello " ; $b .= "There!" ; // sets $b to "Hello There!", just like $b = $b . "There!"; ?>

Note that the assignment copies the original variable to the new one (assignment by value), so changes to one will not affect the other. This may also have relevance if you need to copy something like a large array inside a tight loop.

An exception to the usual assignment by value behaviour within PHP occurs with object s, which are assigned by reference. Objects may be explicitly copied via the clone keyword.

Assignment by Reference

Assignment by reference is also supported, using the " $var = &$othervar; " syntax. Assignment by reference means that both variables end up pointing at the same data, and nothing is copied anywhere.

Example #1 Assigning by reference

The new operator returns a reference automatically, as such assigning the result of new by reference is an error.

The above example will output:

More information on references and their potential uses can be found in the References Explained section of the manual.

Arithmetic Assignment Operators

Bitwise Assignment Operators

Other Assignment Operators

• arithmetic operators
• bitwise operators
• null coalescing operator

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PHP Tutorial

Php advanced, mysql database, php examples, php reference, php operators.

Operators are used to perform operations on variables and values.

PHP divides the operators in the following groups:

• Arithmetic operators
• Assignment operators
• Comparison operators
• Increment/Decrement operators
• Logical operators
• String operators
• Array operators
• Conditional assignment operators

PHP Arithmetic Operators

The PHP arithmetic operators are used with numeric values to perform common arithmetical operations, such as addition, subtraction, multiplication etc.

PHP Assignment Operators

The PHP assignment operators are used with numeric values to write a value to a variable.

The basic assignment operator in PHP is "=". It means that the left operand gets set to the value of the assignment expression on the right.

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PHP Comparison Operators

The PHP comparison operators are used to compare two values (number or string):

PHP Increment / Decrement Operators

The PHP increment operators are used to increment a variable's value.

The PHP decrement operators are used to decrement a variable's value.

PHP Logical Operators

The PHP logical operators are used to combine conditional statements.

PHP String Operators

PHP has two operators that are specially designed for strings.

PHP Array Operators

The PHP array operators are used to compare arrays.

PHP Conditional Assignment Operators

The PHP conditional assignment operators are used to set a value depending on conditions:

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PHP Assignment Operators

In this tutorial, you shall learn about Assignment Operators in PHP, different Assignment Operators available in PHP, their symbols, and how to use them in PHP programs, with examples.

Assignment Operators

Assignment Operators are used to perform to assign a value or modified value to a variable.

Assignment Operators Table

The following table lists out all the assignment operators in PHP programming.

In the following program, we will take values in variables $x and $y , and perform assignment operations on these values using PHP Assignment Operators.

PHP Program

Assignment Operators Tutorials

The following tutorials cover each of the Assignment Operators in PHP in detail with examples.

• PHP Simple Assignment
• PHP Addition Assignment
• PHP Subtraction Assignment
• PHP Multiplication Assignment
• PHP Division Assignment
• PHP Modulus Assignment

In this PHP Tutorial , we learned about all the Assignment Operators in PHP programming, with examples.

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Assignment Operators

The basic assignment operator is "=". Your first inclination might be to think of this as "equal to". Don't. It really means that the left operand gets set to the value of the expression on the right (that is, "gets set to").

The value of an assignment expression is the value assigned. That is, the value of " $a = 3 " is 3. This allows you to do some tricky things: <?php $a  = ( $b  =  4 ) +  5 ;  // $a is equal to 9 now, and $b has been set to 4. ?>

For arrays , assigning a value to a named key is performed using the "=>" operator. The precedence of this operator is the same as other assignment operators.

In addition to the basic assignment operator, there are "combined operators" for all of the binary arithmetic , array union and string operators that allow you to use a value in an expression and then set its value to the result of that expression. For example: <?php $a  =  3 ; $a  +=  5 ;  // sets $a to 8, as if we had said: $a = $a + 5; $b  =  "Hello " ; $b  .=  "There!" ;  // sets $b to "Hello There!", just like $b = $b . "There!"; ?>

Note that the assignment copies the original variable to the new one (assignment by value), so changes to one will not affect the other. This may also have relevance if you need to copy something like a large array inside a tight loop.

An exception to the usual assignment by value behaviour within PHP occurs with object s, which are assigned by reference in PHP 5. Objects may be explicitly copied via the clone keyword.

Assignment by Reference

Assignment by reference is also supported, using the " $var = &$othervar; " syntax. Assignment by reference means that both variables end up pointing at the same data, and nothing is copied anywhere.

Example #1 Assigning by reference

As of PHP 5, the new operator returns a reference automatically, so assigning the result of new by reference results in an E_DEPRECATED message in PHP 5.3 and later, and an E_STRICT message in earlier versions.

For example, this code will result in a warning: <?php class  C  {} /* The following line generates the following error message:  * Deprecated: Assigning the return value of new by reference is deprecated in...  */ $o  = &new  C ; ?>

More information on references and their potential uses can be found in the References Explained section of the manual.

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• Assignment Operators

PHP assignment operators enable you to frequently engage in performing calculations and operations on variables, requiring the assignment of results to other variables. Consequently, this is precisely where assignment operators prove indispensable, allowing you to seamlessly execute an operation and assign the result to a variable within a single statement.

In the following sections, we’ll delve into the different types of PHP assignment operators and explore how to use them.

Table of Contents

Php arithmetic assignment operators, php bitwise assignment operators.

• Null Coalescing Operator

Assigning a Reference to a PHP Variable

Other assignment operators, wrapping up.

The most commonly used assignment operator in PHP is the equals sign (=). For instance, in the following code, the value 10 is assigned to the variable $x:

Now, let’s explore each type with examples:

Numeric data undergoes mathematical operations through the utilization of arithmetic operators. In PHP, this is where arithmetic assignment operators come into play, employed to perform these operations. The arithmetic assignment operators include:

• += or $x + $y (Addition Assignment Operator)
• -= or $x - $y (Subtraction Assignment Operator)
• *= or $x * $y (Multiplication Assignment Operator)
• /= or $x / $y (Division Assignment Operator)
• %= or $x % $y (Modulus Assignment Operator)
• **= or $x ** $y (Exponentiation Assignment Operator)

Consider the following example:

In this example, the addition assignment operator increases the value of $x by 5, and then assigns the result back to $x, producing an output of 15.

You can leverage these arithmetic assignment operators to perform complex calculations in a single statement, making your code more concise and easier to read. For more details, refer to this tutorial .

One crucial aspect of computer science involves the manipulation of binary bits in PHP. Let’s delve into one of the more complex assignment operators—specifically, the PHP bitwise operators.

Developers use bitwise operators to manipulate data at the bit level. PHP bitwise assignment operators perform bitwise operations. Here are the bitwise assignment operators:

• &= or $x & $y (Bitwise AND Assignment Operator)
• |= or $x | $y (Bitwise OR Assignment Operator)
• ^= or $x ^ $y (Bitwise XOR Assignment Operator)
• ~= or $x ~ $y (Bitwise NOT Assignment Operator)
• <<= or $x << $y (Left Shift Assignment Operator)
• >>= or $x >> $y (Right Shift Assignment Operator)

Let’s illustrate with an example:

In this example, a bitwise OR operation is performed between the values of $x and 2 using the bitwise OR assignment operator. The result is then assigned to $x, yielding an output of 7.

Here is a full explanation along with more examples of bitwise operators .

Let’s move to the section below to understand the Null Coalescing Operator in PHP.

Furthermore, developers use the null coalescing operator to assign a default value to a variable if it is null. The double question mark (??) symbolizes the null coalescing operator. Consider the following example:

In this example, the null coalescing operator is used to assign the value ‘John Doe’ to the variable $fullName. If $name is null, the value ‘John Doe’ will be assigned to $fullName.

The null coalescing operator simplifies code by enabling the assignment of default values to variables. By reading this tutorial , you will gain more information about it

Anyway, assigning a reference in PHP is one of the language’s benefits, enabling developers to set a value and refer back to it anywhere during the script-writing process. Let’s move to the section below to take a closer look at this concept.

Furthermore, individuals use the reference assignment operator =& to assign a reference to a variable rather than copying the value of the variable. Consider the following example:

In this example, a reference to the variable $x is created using the reference assignment operator. The value 10 is then assigned to $x, and the output displays the value of $y. Since $y is a reference to $x, it also changes to 10, resulting in an output of 10.

The reference assignment operator proves useful when working with large data sets, enabling you to avoid copying large amounts of data.

Let’s explore some other assignment operators in the paragraphs below.

In addition to the arithmetic, bitwise, null coalescing, and reference assignment operators, PHP provides other assignment operators for specific use cases. These operators are:

• .= (Concatenation Assignment Operator)
• ??= (Null Coalescing Assignment Operator)

Now, let’s explore each of these operators in turn:

Concatenation Assignment Operator: Used to concatenate a string onto the end of another string. For example:

In this example, the concatenation assignment operator appends the value of $string2 to the end of $string1, resulting in the output “Hello World!”.

The Null Coalescing Assignment Operator is employed to assign a default value to a variable when it is detected as null. For example:

In this example, the null coalescing assignment operator assigns the value ‘John Doe’ to the variable $name. If $name is null, the value ‘John Doe’ will be assigned to $name.

Let’s summarize it.

we’ve taken a comprehensive look at the different types of PHP assignment operators and how to use them. Assignment operators are essential tools for any PHP developer, facilitating calculations and operations on variables while assigning results to other variables in a single statement.

Moreover, leveraging assignment operators allows you to make your code more concise, easier to read, and helps in avoiding common programming errors.

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PHP Assignment Operators

Php tutorial index.

PHP assignment operators applied to assign the result of an expression to a variable. = is a fundamental assignment operator in PHP. It means that the left operand gets set to the value of the assignment expression on the right.

• ▼PHP Operators
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PHP Assignment Operators

Description.

Assignment operators allow writing a value to a variable . The first operand must be a variable and the basic assignment operator is "=". The value of an assignment expression is the final value assigned to the variable. In addition to the regular assignment operator "=", several other assignment operators are composites of an operator followed by an equal sign.

Interestingly all five arithmetic operators have corresponding assignment operators, Here is the list.

The following table discussed more details of the said assignment operators.

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Previous: Logical Operators Next: Bitwise Operators

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PHP - assignment operators example

The example below shows the usage of assignment and compound assignment operators:

• = Assignment operator
• += Addition AND assignment operator
• -= Subtraction AND assignment operator
• *= Multiply AND assignment operator
• /= Division AND assignment operator
• **= Exponent AND assignment operator
• %= Modulo AND assignment operator

The output of the above code will be:

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PHP - Assignment Operators Examples

You can use assignment operators in PHP to assign values to variables. Assignment operators are shorthand notations to perform arithmetic or other operations while assigning a value to a variable. For instance, the "=" operator assigns the value on the right-hand side to the variable on the left-hand side.

Additionally, there are compound assignment operators like +=, -= , *=, /=, and %= which combine arithmetic operations with assignment. For example, "$x += 5" is a shorthand for "$x = $x + 5", incrementing the value of $x by 5. Assignment operators offer a concise way to update variables based on their current values.

The following table highligts the assignment operators that are supported by PHP −

The following example shows how you can use these assignment operators in PHP −

It will produce the following output −

• Language Reference
• Classes and Objects

Objects and references

One of the key-points of PHP OOP that is often mentioned is that "objects are passed by references by default". This is not completely true. This section rectifies that general thought using some examples.

A PHP reference is an alias, which allows two different variables to write to the same value. In PHP, an object variable doesn't contain the object itself as value. It only contains an object identifier which allows object accessors to find the actual object. When an object is sent by argument, returned or assigned to another variable, the different variables are not aliases: they hold a copy of the identifier, which points to the same object.

Example #1 References and Objects

The above example will output:

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User contributed notes 17 notes.

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Are multiple variable assignments done by value or reference?

In the above code, are both $a and $b assigned the value of 0 , or is $a just referencing $b ?

• variable-assignment

8 Answers 8

With raw types this is a copy.

With objects though, that is another story (PHP 5)

• 9 Note, that the example is misleading: Changing the property of an object is not the same as changing the variable the object is referenced from. Because the variable never changed, it is of course the same. –  KingCrunch Commented Dec 30, 2011 at 19:00
• 1 According to documentation , PHP uses a copy on write system. It means that with primitive types such as strings or ints are really created in memory on change. That's why, contrary to what we might think, creating references to optimize performance on small variables may not bring the desired effect, because PHP needs to create it before. However, objects are passed by reference by default since PHP5. –  bgondy Commented Apr 11, 2013 at 17:00
• 4 The assign by reference with objects can be changed to assign by copy using clone . EG: $a = clone $b = new Obj; –  Will B. Commented Mar 31, 2016 at 21:17
• At the class variable declaration level how it would be ? Like this private $_name = $address = ""; –  Chaminda Bandara Commented Nov 14, 2016 at 10:12

Regard this code as:

The expression $b = 0 not only assigns 0 to $b , but it yields a result as well. That result is the right part of the assignment, or simply the value that $b got assigned to.

So, $a gets assigned 0 as well.

You could have tried it yourself

(currently I dont really care :D)

Thus: No, they are both independent variables with the value 0 .

• In that example, wouldn't you have to assign 5 to $b on the second line to prove the reference was not present? and yes, you are correct. I figured having the question up here would be nice for others searching as well though... –  Evil Elf Commented Jun 6, 2011 at 19:47
• @Evil: Don't want to think about it, so added the other way round too. Both return 0 , thus it must be true in any case :) –  KingCrunch Commented Jun 6, 2011 at 19:49

I'll recommend a good read on this: http://terriswallow.com/weblog/2007/multiple-and-dynamic-variable-assignment-in-php/ . In one of comments, you can read:

It should be noted that if you use multiple assignment on one line to assign an object, the object is assigned by reference. Therefore, if you change the value of the object’s property using either variable, the value essentially changes in both.

So I'll personally recommend that you assign the variables separately.

For the record:

So the conclusion is that there is no reference for primitives, but there IS a reference to objects.

• we proved this false actually with some tests. –  Evil Elf Commented Jun 6, 2011 at 20:15

It depends what're you assigning.

If you're assigning a value, then the assignment copies the original variable to the new one.

Above code will return 0 as it's assignment by value.

An exception to the usual assignment by value behaviour within PHP occurs with objects, which are assigned by reference in PHP 5 automatically. Objects may be explicitly copied via the clone keyword.

Above code will print <html></html> .

Both $a and $b are assigned that value of 0. If you wanted $a to reference $b, you would preempt it with an ampersand, e.g.:

http://php.net/manual/en/language.oop5.basic.php

its assigns them both the value of 0

is the same as

Setting a variable equal to an existing object in PHP will pass by REFERENCE. It will not do a deep copy unless you add the clone keyword.

Long chains

This pattern applies to longer chains too.

You can confirm using a PHP sandbox: https://onlinephp.io/c/7b70f

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