# soundex

(PHP 4, PHP 5, PHP 7)

soundex — Calculate the soundex key of a string

### 说明

soundex ( string `$str` ) : string

Calculates the soundex key of `str`.

Soundex keys have the property that words pronounced similarly produce the same soundex key, and can thus be used to simplify searches in databases where you know the pronunciation but not the spelling. This soundex function returns a string 4 characters long, starting with a letter.

This particular soundex function is one described by Donald Knuth in "The Art Of Computer Programming, vol. 3: Sorting And Searching", Addison-Wesley (1973), pp. 391-392.

### 参数

`str`

  The input string.

### 返回值

Returns the soundex key as a string.

### 范例

Example #1 Soundex Examples

    <?php
    soundex("Euler")       == soundex("Ellery");    // E460
    soundex("Gauss")       == soundex("Ghosh");     // G200
    soundex("Hilbert")     == soundex("Heilbronn"); // H416
    soundex("Knuth")       == soundex("Kant");      // K530
    soundex("Lloyd")       == soundex("Ladd");      // L300
    soundex("Lukasiewicz") == soundex("Lissajous"); // L222
    ?>

### 参见

- levenshtein() - 计算两个字符串之间的编辑距离
- metaphone() - Calculate the metaphone key of a string
- similar_text() - 计算两个字符串的相似度