{"id":423,"date":"2021-03-15T07:48:22","date_gmt":"2021-03-15T07:48:22","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=423"},"modified":"2025-04-05T14:56:29","modified_gmt":"2025-04-05T14:56:29","slug":"php-or-operator","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-or-operator\/","title":{"rendered":"PHP OR Operator"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about the PHP OR operator (||) and how to use it to build complex logical expressions.<\/p>\n\n\n\n

Introduction to the PHP OR operator #<\/a><\/h2>\n\n\n\n

The logical OR<\/code> operator accepts two operands and returns true<\/code> if either operand is true; otherwise, it returns false<\/code>. In other words, the logical OR operator returns false<\/code> if both operands are false<\/code>.<\/p>\n\n\n\n

To represent the logical OR operator, PHP uses either the or<\/code> keyword or the ||<\/code> as follows:<\/p>\n\n\n

expression1 or<\/span> expression2<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Or<\/p>\n\n\n
expression1 || expression2<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The following table illustrates the result of the or<\/code> operator:<\/p>\n\n\n\n
expression1<\/th>expression2<\/th>expression1 || expression2<\/th><\/tr><\/thead>
true<\/code><\/td>true<\/code><\/td>true<\/code><\/td><\/tr>
true<\/code><\/td>false<\/code><\/td>true<\/code><\/td><\/tr>
false<\/code><\/td>true<\/code><\/td>true<\/code><\/td><\/tr>
false<\/code><\/td>false<\/code><\/td>false<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Note that the or<\/code>, Or<\/code>, and OR<\/code> are the same because PHP keywords are case-insensitive.<\/p>\n\n\n\n
The ||<\/code> and or<\/code> operators return the same result. The only difference between the ||<\/code> and or<\/code> operators are their precedences. The or<\/code> operator has higher precedence than the ||<\/code> operator.<\/p>\n\n\n\n
PHP OR operator examples #<\/a><\/h2>\n\n\n\n
Suppose that you need to clear the cache of the website if the flag $exprired<\/code> or $purge<\/code> is set to true<\/code>. To do that, you can use the logical OR operator as follows:<\/p>\n\n\n
<?php<\/span>\n\n$expired = true<\/span>;\n$purged = false<\/span>;\n\n$clear_cache = $expired || $purged;\n\nvar_dump($clear_cache);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
bool(true<\/span>)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Since $expired<\/code> is true<\/code>, the result of the OR operator is also true<\/code>.<\/p>\n\n\n\n
However, if you change the $expired<\/code> to false<\/code>, the result will be false<\/code> as shown in the following example:<\/p>\n\n\n
<?php<\/span>\n\n$expired = false<\/span>;\n$purged = false<\/span>;\n\n$clear_cache = $expired || $purged;\n\nvar_dump($clear_cache);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In practice, you often use the logical OR operator in the if<\/a>, if-else<\/a>, if-elseif<\/a>, while<\/a>, and do-while <\/a>statements.<\/p>\n\n\n\n
Short-circuiting #<\/a><\/h2>\n\n\n\n
When the first operand is true<\/code>, the logical OR operator knows that the result must be also true<\/code>. In this case, it doesn’t evaluate the second operand. This process is called short-circuiting.<\/p>\n\n\n\n
In practice, you often find that the or operator is used in the following pattern:<\/p>\n\n\n
function_call() || die<\/span>(message)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
If the function_call()<\/code> returns true<\/code>, it succeeded. PHP will never execute the second operand which is a call to the die()<\/code> function. Otherwise, PHP will call the die()<\/code> function with an error message.<\/p>\n\n\n\n
For example:<\/p>\n\n\n
<?php<\/span>\n\nfunction<\/span> connect_to_db<\/span>()<\/span>\n<\/span>{\n\treturn<\/span> false<\/span>;\n}\n\nconnect_to_db() || die<\/span>('Cannot connect to the database.'<\/span>);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Cannot connect to the database<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, the connect_to_db()<\/code> function returns false<\/code>, PHP calls the die()<\/code> function that shows the error message.<\/p>\n\n\n\n
The PHP OR gotchas #<\/a><\/h2>\n\n\n\n
See the following example:<\/p>\n\n\n
<?php<\/span>\n\n$result = false<\/span> or<\/span> true<\/span>;\n\nvar_dump($result);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
bool(false<\/span>)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, you would expect that the $result is true because false or true expression returns true. However, this is not the case.<\/p>\n\n\n\n
When evaluating the following statement:<\/p>\n\n\n
$result = false<\/span> or<\/span> true<\/span>;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
PHP evaluates the $result = false<\/code> first and then the or<\/code> operator second because the =<\/code> operator has higher precedence than the or<\/code> operator.<\/p>\n\n\n\n
Notice that each operator has precedence. And PHP will evaluate the operators with the higher precedence before the ones with the lower precedence.<\/p>\n\n\n\n
Technically, it is equivalent to the following:<\/p>\n\n\n
($result = false<\/span>) or<\/span> true<\/span>;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Therefore, $result<\/code> is assigned the false<\/code> value.<\/p>\n\n\n\n
To fix this, you need to use parentheses to change the order of evaluation:<\/p>\n\n\n
<?php<\/span>\n\n$result = (false<\/span> or<\/span> true<\/span>);\n\nvar_dump($result);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
bool(true<\/span>)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Or you can use the || operator:<\/p>\n\n\n
<?php<\/span>\n\n$result = false<\/span> || true<\/span>;\nvar_dump($result);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
bool(true<\/span>)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Therefore, it’s a good practice to use the ||<\/code> operator instead of the or<\/code> operator.<\/p>\n\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
    \n
  • Use the PHP OR operator (or<\/code>, ||<\/code>) to combine two expressions and returns true<\/code> if either expression is true<\/code>; otherwise, it returns false<\/code>.<\/li>\n\n\n\n
  • The logical OR operator is short-circuiting.<\/li>\n\n\n\n
  • Do use the ||<\/code> operator instead of the or<\/code> operator.<\/li>\n<\/ul>\n
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