PHP supports variable length argument function. It means you can pass 0, 1 or n number of arguments in function. To do this, you need to use 3 ellipses (dots) before the argument name. The 3 dot concept is implemented for variable length argument since PHP 5.6.

In PHP, you can create functions that accept a variable number of arguments using what’s called “variable-length argument lists” or “variadic functions”. This feature allows you to define functions that can take a different number of arguments each time they are called.

In PHP, you can define a variable-length argument function using the func_get_args() function within the function body. Here’s a simple example:

php

function sum() {

    $args = func_get_args();

    $total = 0;

    foreach ($args as $arg) {

        $total += $arg;

    }

    return $total;

}

echo sum(1, 2, 3); // Outputs: 6 echo sum(4, 5, 6, 7); // Outputs: 22

In this example, the sum() function accepts any number of arguments passed to it. Inside the function, func_get_args() is used to retrieve all the arguments passed to the function as an array. Then, it simply iterates over this array, adding up all the values.

Alternatively, since PHP 5.6, you can use the ... (ellipsis) operator to define a variable-length argument list explicitly. Here’s the same example using this syntax:

php

function sum(...$numbers) {

    $total = 0;

    foreach ($numbers as $number) {

        $total += $number;

    }

    return $total;

}

echo sum(1, 2, 3); // Outputs: 6 echo sum(4, 5, 6, 7); // Outputs: 22

Using the ellipsis operator ...$numbers, you directly specify that the function can accept any number of arguments, and they will be collected into the $numbers array. This syntax is more concise and easier to read.

In summary, a PHP variable-length argument function is a function that can accept a variable number of arguments, and you can handle these arguments within the function body using func_get_args() or the ... operator.