The soundex() function is a built-in function in PHP and is used to calculate the Soundex key of a given string.
The soudex key is a four character long alphanumeric string(starting with a letter) which represents the English pronunciation of the given string.
Parameters: This function accepts a single parameter $str which represents the string for which we want to find the Soundex key.
Return Value: It returns the soundex key as a string.
Below programs illustrate the soundex() function in PHP:
Program 1: In the below program, the soudex() function generates the soundex key of the string “geeksforgeeks”.
Program 2: In the below program, we will see that two words having same pronunciation produce similar Soundex key.