[Solved] You have a function declared as:function transform(array $data, callable $callback) { return array_map($callback, $data); }Which of the following calls is valid? | PHP

PHP - Functions

You have a function declared as:

function transform(array $data, callable $callback) {
    return array_map($callback, $data);
}

Which of the following calls is valid?

Atransform([1, 2, 3], 'not_a_function');

Btransform([1, 2, 3], null);

Ctransform([1, 2, 3], 123);

Dtransform([1, 2, 3], fn($x) => $x * 2);

Step-by-Step Solution

Solution:

Step 1: Understand callable type declaration
Parameter declared as callable must be a valid function or closure.
Step 2: Check each call
transform([1, 2, 3], fn($x) => $x * 2); passes a valid arrow function. transform([1, 2, 3], 'not_a_function'); passes a string not referencing a function. transform([1, 2, 3], 123); passes an integer. transform([1, 2, 3], null); passes null. Only B is valid.
Final Answer:
transform([1, 2, 3], fn($x) => $x * 2); -> Option D
Quick Check:
Callable parameter requires valid function or closure [OK]

Quick Trick: Callable parameters accept functions or closures only [OK]

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