Generator::key

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

Generator::key — Get the yielded key

Description

public Generator::key(): mixed

Gets the key of the yielded value.

Parameters

This function has no parameters.

Return Values

Returns the yielded key.

Examples

Example #1 Generator::key() example

<?php

function Gen()
{
    yield 'key' => 'value';
}

$gen = Gen();

echo "{$gen->key()} => {$gen->current()}";

The above example will output:

key => value

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User Contributed Notes 1 note

down

jasonrlester at yahoo dot com ¶

2 years ago

This is important when considering how other Generators work such as JavaScript's an Python's. While PHP's generator has the ->valid() method they don't, or an equivalent. JS uses Iterator protocol which says next() should return an object of

{
    done: bool,
    value: mixed
}

In which case you can use keys->done to see if the generator can still be iterated.

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