# levenshtein

(PHP 3 >= 3.0.17, PHP 4 >= 4.0.1, PHP 5)

levenshtein -- Calculate Levenshtein distance between two strings## Description

int**levenshtein**( string str1, string str2 [, int cost_ins, int cost_rep, int cost_del] )

This function returns the Levenshtein-Distance between the two argument strings or -1, if one of the argument strings is longer than the limit of 255 characters.

The Levenshtein distance is defined as the minimal number of
characters you have to replace, insert or delete to transform
`str1`

into `str2`

.
The complexity of the algorithm is `O(m*n)`,
where `n` and `m` are the
length of `str1`

and
`str2`

(rather good when compared to
**similar_text()**, which is O(max(n,m)**3),
but still expensive).

In its simplest form the function will take only the two
strings as parameter and will calculate just the number of
insert, replace and delete operations needed to transform
`str1`

into `str2`

.

A second variant will take three additional parameters that define the cost of insert, replace and delete operations. This is more general and adaptive than variant one, but not as efficient.

See also **soundex()**,
**similar_text()**, and
**metaphone()**.