You want to reverse the words or the bytes in a string.
Use strrev( ) to reverse by byte, as in Example 1-19.
Reversing a string by byte
Example 1-19 prints:
.emordnilap a ton si sihT
To reverse by words, explode the string by word boundary, reverse the words, and then rejoin, as in Example 1-20.
Reversing a string by word
Example 1-20 prints:
turtle. a was there time a upon Once
Reversing a string by words can also be done all in one line with the code in Example 1-21.
Concisely reversing a string by word
1.5.4. See Also
Recipe 23.7 discusses the implications of using something other than a space character as your word boundary; documentation on strrev( ) at http://www.php.net/strrev and array_reverse( ) at http://www.php.net/array-reverse.