PHP String metaphone() Function

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The PHP String metaphone() function is used to calculate the metaphone key of a string. A phonetic approach for indexing words based on pronunciation is the Metaphone key. It takes advantage of the more comprehensive set of English pronunciation rules.

Similar to soundex(), metaphone generates the same key for words that sound similar. It is more accurate than soundex() because it understands the fundamental rules of English pronunciation. The metaphone-generated keys are of varying lengths.

Syntax

Below is the syntax of the PHP String metaphone() function −

string metaphone ( string $str [, int $phonemes = 0 ] )

Parameters

Here are the parameters of the metaphone() function −

• $str − It contains the information about input string.

• $phonemes − It specifies the length of metaphone key. But since the phonemes are always completely transcribed, the final string length can vary somewhat greater than max_phonemes. The default value of zero indicates no restriction.

Return Value

The metaphone() function returns the metaphone key as a string, or FALSE on failure.

PHP Version

First introduced in core PHP 4, the metaphone() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

Here is the basic example of the PHP String metaphone() function in which we will calculates the metaphone key of a simple word.

<?php
   // Basic usage of metaphone
   $word = "example";
   $metaphoneKey = metaphone($word);

   echo "Metaphone key of '$word': $metaphoneKey\n";
?>

Output

Here is the outcome of the following code −

Metaphone key of 'example': EKSMPL

Example 2

In the below PHP code we will use the metaphone() function and demonstrates how to limit the length of the metaphone key. The metaphone key is limited to a given length (4). This is useful for working with limited storage or comparing data.

<?php
   // Using metaphone with a given length
   $word = "phonetics";
   $length = 4;
   $metaphoneKey = metaphone($word, $length);

   echo "Metaphone key of '$word' (length $length): $metaphoneKey";
?> 

Output

This will generate the below output −

Metaphone key of 'phonetics' (length 4): FNTK

Example 3

Now the below code calculates metaphone keys for an array of words. This example uses multiple words to show how similar-sounding words can have the same metaphone keys, which is useful for phonetic comparison.

<?php
   // Generate metaphone keys for multiple words
   $words = ["cat", "kat", "cot", "cut"];
   echo "Word\tMetaphone Key\n";
   echo "--------------------\n";

   foreach ($words as $word) {
      $metaphoneKey = metaphone($word);
      echo "$word\t$metaphoneKey\n";
   }
?> 

Output

This will create the below output −

Word    Metaphone Key
--------------------
cat     KT
kat     KT
cot     KT
cut     KT

Example 4

This program shows how to use metaphone to create a simple phonetic search.

<?php
   // Phonetic search in a dictionary 
   $dictionary = ["phone", "fawn", "fun", "fan", "phony"];
   $search = "fon";
   $searchKey = metaphone($search);

   echo "Searching for words similar to '$search'...\n";
   echo "Matches:\n";

   foreach ($dictionary as $word) {
      if (metaphone($word) === $searchKey) {
         echo "$word\n";
      }
   }
?> 

Output

Following is the output of the above code −

Searching for words similar to 'fon'...
Matches:
phone
fawn
fun
fan
phony