[lang-ref] ( dict_reverse_lookup ) ( php )

<?php
public function testDictReverseLookup(): void
{
	// array_flip
	$d = [ 'A' => 1, 'B' => 2, 'C' => 3, 'D' => 2, 'E' => 1 ];

	$reverseDict = array_flip($d);

	$this->assertSame('C', $reverseDict[3]);
	$this->assertSame('E', $reverseDict[1]); // last one wins
}

<?php
public function testDictReverseLookupAlternative(): void
{
	// array_search($v, $d)
	$d = [ 'A' => 1, 'B' => 2, 'C' => 3, 'D' => 2 ];

	$key = array_search(2, $d, strict: true);
	$this->assertSame('B', $key); // first one wins

	$key = array_search(4, $d, strict: true);
	$this->assertFalse($key); // not found: false is returned, not null
}