Get the yielded key

# Generator::key

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

Generator::key — Get the yielded key

### Description

public function 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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