Change a string based on a pattern

I want to change a string in PHP by 开发者_开发技巧deleting the first and the last char but ONLY IF they are equal.

Let me give some examples:

' abc ' should become 'abc'
'abc a' should become 'bc '
' abc a' should not change

How do I do it?

Thanks for the help, the regex based solution works.

You can use the regex:

$str = preg_replace('~^(.)(.*)\1$~','$2',$str);

Regex explanation:

• ~ : Delimiters
• ^ : Start anchor
• (.) : match and remember a char ( here its the first char)
• (.*) : match anything and remember
• \1 : recall the first match
• $ : End anchor
• $2 : recall the 2nd match

Alternatively you can do:

// if string has >1 char and 1st and last char as same.
if(strlen($str) > 1 && $str[0] == $str[strlen($str)-1]) {
  $str = substr($str,1,strlen($str)-2); // extract the substring
}