Different tips and options for PHP function calls

PHP language provides a variety of function calling techniques, including: standard function calling, using variables as function names and function pointers. By using function pointers, programmers can pass functions as arguments to other functions or callbacks. For example, we can pass the check_user() function as a callback function to array_filter() using a function pointer to filter out the array of users who failed validation.

Different techniques and options for PHP function calling

The PHP language provides a variety of methods to call functions, which is convenient for programmers to Choose the most appropriate technology for a specific scenario. The following are commonly used function calling techniques and options:

1. Standard function call

This is the most basic function calling method, directly using the function name and passing parameters. For example:

function calculate_total($price, $quantity) {
    return $price * $quantity;
}

$total = calculate_total(10, 5); // 返回 50

2. Use variables as function names

You can use variables to store function names, which allows dynamic calling of functions at runtime. For example:

$function_name = "calculate_total";
$param1 = 10;
$param2 = 5;
call_user_func($function_name, $param1, $param2); // 返回 50

3. Function pointer

A function pointer is a reference to a function and can be created using the fn keyword. This makes it possible to pass functions as arguments to other functions or callbacks. For example:

$func = fn($x, $y) => $x + $y;

Practical case:

Suppose we have a function check_user(), used to verify user identity. We can pass this function as a callback function to array_filter() using a function pointer to filter out the array of users that failed validation.

function check_user($user) {
    return $user['is_verified'];
}

$users = [
    ['name' => 'John Doe', 'is_verified' => true],
    ['name' => 'Jane Doe', 'is_verified' => false],
];

$verified_users = array_filter($users, 'check_user');

This way, $verified_users contains only verified users.

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