php if with assignment

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Summary : in this tutorial, you’ll learn about the PHP if statement and how to use it to execute a code block conditionally.

Introduction to the PHP if statement

The if statement allows you to execute a statement if an expression evaluates to true . The following shows the syntax of the if statement:

In this syntax, PHP evaluates the expression first. If the expression evaluates to true , PHP executes the statement . In case the expression evaluates to false , PHP ignores the statement .

The following flowchart illustrates how the if statement works:

The following example uses the if statement to display a message if the $is_admin variable sets to true :

Since $is_admin is true , the script outputs the following message:

Curly braces

If you want to execute multiple statements in the if block, you can use curly braces to group multiple statements like this:

The following example uses the if statement that executes multiple statements:

In this example, the if statement displays a message and sets the $can_edit variable to true if the $is_admin variable is true .

It’s a good practice to always use curly braces with the if statement even though it has a single statement to execute like this:

In addition, you can use spaces between the expression and curly braces to make the code more readable.

Nesting if statements

It’s possible to nest an if statement inside another if statement as follows:

The following example shows how to nest an if statement in another if statement:

Embed if statement in HTML

To embed an if statement in an HTML document, you can use the above syntax. However, PHP provides a better syntax that allows you to mix the if statement with HTML nicely:

The following example uses the if statement that shows the edit link if the $is_admin is true :

Since the $is_admin is true , the script shows the Edit link. If you change the value of the $is_admin to false , you won’t see the Edit link in the output.

A common mistake with the PHP if statement

A common mistake that you may have is to use the wrong operator in the if statement. For example:

This script shows a message if the $checke d is 'off' . However, the expression in the if statement is an assignment, not a comparison:

This expression assigns the literal string 'off' to the $checked variable and returns that variable. It doesn’t compare the value of the $checked variable with the 'off' value. Therefore, the expression always evaluates to true , which is not correct.

To avoid this error, you can place the value first before the comparison operator and the variable after the comparison operator like this:

If you accidentally use the assignment operator (=), PHP will raise a syntax error instead:

• The if statement executes a statement if a condition evaluates to true .
• Always use curly braces even if you have a single statement to execute in the if statement. It makes the code more obvious.
• Do use the pattern if ( value == $variable_name ) {} to avoid possible mistakes.

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Php advanced, mysql database, php examples, php reference, php if statements.

Conditional statements are used to perform different actions based on different conditions.

PHP Conditional Statements

Very often when you write code, you want to perform different actions for different conditions. You can use conditional statements in your code to do this.

In PHP we have the following conditional statements:

• if statement - executes some code if one condition is true
• if...else statement - executes some code if a condition is true and another code if that condition is false
• if...elseif...else statement - executes different codes for more than two conditions
• switch statement - selects one of many blocks of code to be executed

PHP - The if Statement

The if statement executes some code if one condition is true.

Output "Have a good day!" if 5 is larger than 3:

We can also use variables in the if statement:

Output "Have a good day!" if $t is less than 20:

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Conditional Assignment Operator in PHP is a shorthand operator that allow developers to assign values to variables based on certain conditions.

Ternary Operator Syntax

The null coalescing operator (), the null coalescing assignment operator (=), the elvis operator (:), wrapping up.

In this article, we will explore how the various Conditional Assignment Operators in PHP simplify code and make it more readable.

Let’s begin with the ternary operator.

The Conditional Operator in PHP, also known as the Ternary Operator, assigns values to variables based on a certain condition. It takes three operands: the condition, the value to be assigned if the condition is true, and the value to be assigned if the condition is false.

Here’s an example:

In this example, the condition is  $score >= 60 . If this condition is true, the value of  $result  is “Pass”. Otherwise, the value of  $result  is “Fail”.

To learn more, visit the  PHP ternary operator tutorial . Let’s now explore the section below to delve into the Null Coalescing Operator in PHP.

The Null Coalescing Operator, also known as the Null Coalescing Assignment Operator, assigns a default value to a variable if it is null. The operator has two operands: the variable and the default value it assigns if the variable is null. Here’s an example:

So, In this example, if the  $_GET['name']  variable is null, the value of  $name  is “Guest”. Otherwise, the value of  $name  is the value of  $_GET['name'] .

Here’s another pattern utilizing it with the assignment operator. Let’s proceed.

The  Null Coalescing Operator  with Assignment, also known as the Null Coalescing Assignment Operator, assigns a default value to a variable if it is null. The operator has two operands: the variable and the default value it assigns if the variable is null. Here’s an example:

So, the value of  $name  is null. The Null Coalescing Assignment Operator assigns the value “Guest” to $name. Therefore, the output of the echo statement is “Welcome,”Guest!”.

Moving into the following section, you’ll learn how to use the Elvis operator in PHP.

In another hand, The  Elvis Operator  is a shorthand version of the Ternary Operator. Which assigns a default value to a variable if it is null. It takes two operands: the variable and the default value to be assigned if the variable is null. Here’s an example:

In this example, if the  $_GET['name']  variable is null, the value“Guest” $name s “Guest”. Otherwise, the value of  $name  is the value of  $_GET['name'] .

Let’s summarize it.

The Conditional Assignment Operators in PHP provide developers with powerful tools to simplify code and make it more readable. You can use these operators to assign values to variables based on certain conditions, assign default values to variables if they are null, and perform shorthand versions of conditional statements. By using these operators, developers can write more efficient and elegant code.

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PHP Variable Assignment Within If Statement

The usual practice when checking for the return value of functions is to run the function and store the value in a variable, and then test that variable. Here is an example of that process using the strstr() function.

There is another way to write the same code within a single if statement. The following example assigns the variable and checks the return value in a single line of code.

There is one problem with assigning variables in this way, and this is that you can only do one. If you try to assign more than one variable at a time you will find that everything but the final variable will turn out to be the outcome of the boolean comparison. Take the following example, which uses the same $string variable as the other examples.

The first two comparisons come out as true and so $var1 and $var2 are assigned boolean values of true. The final comparison is the only one that is assigned the expected value. This might be a bug in PHP, but as this is a non-standard way of assigning variables I don't think many people have come across it.

Submitted by James Bower on Mon, 09/07/2009 - 21:17

Submitted by Mirek Suk on Tue, 09/28/2010 - 12:08

Name Philip Norton

Submitted by giHlZp8M8D on Wed, 09/29/2010 - 08:56

Submitted by Jim on Sun, 11/07/2010 - 23:09

This works too: if( !($val = $arg) ) { $val = 'default'; }

Submitted by Frank on Mon, 05/02/2011 - 17:52

Submitted by Vishal on Sun, 05/17/2015 - 09:24

Submitted by Jesus on Tue, 03/20/2018 - 14:55

Submitted by giHlZp8M8D on Tue, 03/20/2018 - 15:19

Submitted by Russ on Fri, 05/31/2019 - 18:18

Submitted by Sam on Fri, 05/15/2020 - 21:30

For fixed payment types, you may be better off to assign an array with the options, with the code as key, and display name as value. That array could be filled from a database query on payment types allowed, which would then pick up when you add a new option, you don't then have to re-code so much.

Submitted by Peter H on Fri, 06/05/2020 - 12:24

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elseif/else if

(PHP 4, PHP 5, PHP 7, PHP 8)

elseif , as its name suggests, is a combination of if and else . Like else , it extends an if statement to execute a different statement in case the original if expression evaluates to false . However, unlike else , it will execute that alternative expression only if the elseif conditional expression evaluates to true . For example, the following code would display a is bigger than b , a equal to b or a is smaller than b : <?php if ( $a > $b ) { echo "a is bigger than b" ; } elseif ( $a == $b ) { echo "a is equal to b" ; } else { echo "a is smaller than b" ; } ?>

There may be several elseif s within the same if statement. The first elseif expression (if any) that evaluates to true would be executed. In PHP, it's possible to write else if (in two words) and the behavior would be identical to the one of elseif (in a single word). The syntactic meaning is slightly different (the same behavior as C) but the bottom line is that both would result in exactly the same behavior.

The elseif statement is only executed if the preceding if expression and any preceding elseif expressions evaluated to false , and the current elseif expression evaluated to true .

Note : Note that elseif and else if will only be considered exactly the same when using curly brackets as in the above example. When using a colon to define if / elseif conditions, the use of elseif in a single word becomes necessary. PHP will fail with a parse error if else if is split into two words.

<?php /* Incorrect Method: */ if ( $a > $b ): echo $a . " is greater than " . $b ; else if ( $a == $b ): // Will not compile. echo "The above line causes a parse error." ; endif; /* Correct Method: */ if ( $a > $b ): echo $a . " is greater than " . $b ; elseif ( $a == $b ): // Note the combination of the words. echo $a . " equals " . $b ; else: echo $a . " is neither greater than or equal to " . $b ; endif; ?>

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Set variable in if statement expression

I ran across some interesting code today. I tried to find out if this is a feature of PHP or if I am missing something, but was unable to find anything on Google. Probably because I don't know the name of it.

The variable $logo is not being set anywhere else. It seems like the expression in this if statement is checking to see if the that class method is returning anything and simultaneously setting the variable $logo to be used in the statement.

Is this true? If so, what in the world is this called!?!

• if-statement

• 2 first it assigns, then evaluates the return value of the assignment which is the assigned result. –  bwoebi Commented Apr 18, 2013 at 20:49

2 Answers 2

You can make an assignment like that in a conditional. What happened logically is that the value is assigned to $logo and then $logo is evaluated as to whether it is truthy. If it is truthy, the code in the conditional executes.

You will oftentimes see this sort of assignment/evaluation in the case of looping through database result sets, but generally I would suggest that it should be avoided outside such a common use case for sake of clarity in reading g code.

• That's what I thought, but I can't seem to find any official documentation on it. Is there a name for it? I want to read the docs about it. –  Chris Bier Commented Apr 18, 2013 at 20:49
• 2 @ChrisB: It's just how the assignment operator works. It returns the assigned value. Docs: php.net/manual/en/language.operators.assignment.php –  gen_Eric Commented Apr 18, 2013 at 20:51
• @RocketHazmat I guess I just didn't know you could do that inside of an if statement's expression –  Chris Bier Commented Apr 18, 2013 at 20:52
• @ChrisB: The = is just an operator, like + or * . It can be used it lots of places :-) –  gen_Eric Commented Apr 18, 2013 at 20:53
• 2 @ChrisB Generally, use of the assignment operator in a conditional like this should be frowned upon (IMO at least). There are however the handful of cases like looping through a result set of unknown length where it makes sense for example something like: while($row = $db_result->fetch(){ ... } . But in this case my preference would have been to put the assignment on a separate line of code before the conditional. I think this code is more readable and less error prone that way. –  Mike Brant Commented Apr 18, 2013 at 20:56

Yes, this is a feature. It's like:

But in this case, imagine the bool result of if as var $a.

However, IDE's are used to complain about solutions like this because of == vs. = as a very common possible bug source.

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