{"id":463,"date":"2021-03-17T01:19:17","date_gmt":"2021-03-17T01:19:17","guid":{"rendered":"https:\/\/phptutorial.net\/?page_id=463"},"modified":"2025-04-06T02:08:54","modified_gmt":"2025-04-06T02:08:54","slug":"php-function-parameters","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/php-function-parameters\/","title":{"rendered":"PHP Function Parameters"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about the function parameters and pass arguments by value and reference.<\/p>\n\n\n\n

Introduction to the PHP function parameters #<\/a><\/h2>\n\n\n\n

A function<\/a> can have zero or more parameters:<\/p>\n\n\n

<?php<\/span>\n\nfunction<\/span> function_name<\/span>(parameter_list)<\/span> \n<\/span>{\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
When a function has multiple parameters, you need to separate them using a comma (,<\/code>).<\/p>\n\n\n\n
The following example defines the concat()<\/code> function that concatenates two strings into one:<\/p>\n\n\n
<?php<\/span>\n\nfunction<\/span> concat<\/span>($str1, $str2)<\/span>\n<\/span>{\n\treturn<\/span> $str1 . $str2;\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The concat()<\/code> function has two parameters $str1<\/code> and $str2<\/code>.<\/p>\n\n\n\n
When you call the concat()<\/code> function, you need to pass two arguments that correspond to the parameters. For example:<\/p>\n\n\n
<?php<\/span>\n\nfunction<\/span> concat<\/span>($str1, $str2)<\/span>\n<\/span>{\n\treturn<\/span> $str1 . $str2;\n}\n\n$greeting = concat('Welcome '<\/span>, 'Admin'<\/span>);\necho<\/span> $greeting;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, the $str1<\/code> will take the first argument 'Welcome '<\/code>, and the $str2<\/code> will take the second argument 'Admin'<\/code>.<\/p>\n\n\n\n
PHP will raise an error if the number of arguments you pass to the function is less than the number of parameters. For example:<\/p>\n\n\n
<?php<\/span>\n\nfunction<\/span> concat<\/span>($str1, $str2)<\/span>\n<\/span>{\n\treturn<\/span> $str1 . $str2;\n}\n\n\n$greeting = concat('Welcome'<\/span>);\necho<\/span> $greeting;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
When you pass multiple arguments to a function, you can break the list the arguments vertically to make the code more readable like this:<\/p>\n\n\n
<?php<\/span>\n\nfunction<\/span> concat<\/span>($str1, $str2)<\/span>\n<\/span>{\n\treturn<\/span> $str1 . $str2;\n}\n\n$greeting = concat(\n\t'Welcome '<\/span>,\n\t'Home'<\/span>\n);\n\necho<\/span> $greeting;<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
It’s a good practice to list arguments vertically when the argument list is long.<\/p>\n\n\n\n
Trailing comma (,) #<\/a><\/h2>\n\n\n\n
From PHP 7.0, the argument list may contain a trailing comma (,<\/code>), which the PHP interpreter will ignore. For example:<\/p>\n\n\n
$greeting = concat(\n\t'Welcome '<\/span>,\n\t'Home'<\/span>,\n);<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Starting from PHP 8.0, you can place the trailing comma (,) in the parameter list like this:<\/p>\n\n\n
function<\/span> concat<\/span>(\n\t$str1,\n\t$str2,\n)<\/span> <\/span>{\n\treturn<\/span> $str1 . $str2;\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Passing arguments by values #<\/a><\/h2>\n\n\n\n
Consider the following example:<\/p>\n\n\n
<?php<\/span>\n\n$counter = 1<\/span>;\nfunction<\/span> increase<\/span>($value)<\/span>\n<\/span>{\n\t$value+= 1<\/span>;\n\techo<\/span> $value. '<br>'<\/span>; \/\/ 2<\/span>\n}\n\n\/\/ increase the counter<\/span>\nincrease($counter);\n\necho<\/span> $counter . '<br>'<\/span>; \/\/ 1<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
2<\/span>\n1<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n