ereg_replace to preg_replace?

Question

How can I convert

ereg_replace(".*\.(.*)$","\\1",$imgfile);

to

preg_replace... ?

?

I'm having trouble with it?

Lemuel

Answer 1

preg_replace("/.*\.(.*)$/", "\\1", "foo.jpg")

I don't know why PHP requires the / delimiters. The only reason Perl, JS, etc. have them is that they allow regex literals, which PHP doesn't.

Devon

It is because they opt to use the single string to provide both the modifier and the regex pattern. "/[a-z]/i". – Lyell

See php.net/manual/en/regexp.reference.delimiters.php .. for example, $a = 'string/with/slashes'; $b = preg_replace('#/with/#', '-without-', $a); is valid, sets $b to string-without-slashes and you do not have to escape the / in the regex given to preg_replace. – Jahn

Answer 2

You should know 4 main things to port ereg patterns to preg:

1. Add delimiters(/): 'pattern' => '/pattern/'

2. Escape delimiter if it is a part of the pattern: 'patt/ern' => '/patt\/ern/'
   Achieve it programmatically in following way:
   $ereg_pattern = '<div>.+</div>';
$preg_pattern = '/' .addcslashes($ereg_pattern, '/') . '/';

3. eregi(case-insensitive matching): 'pattern' => '/pattern/i' So, if you are using eregi function for case insenstive matching, just add 'i' in the end of new pattern('/pattern/').

4. ASCII values: In ereg, if you use number in the pattern, it is assumed that you are referring to the ASCII of a character. But in preg, number is not treated as ASCII value. So, if your pattern contain ASCII value in the ereg expression(for example: new line, tabs etc) then convert it to hexadecimal and prefix it with \x.
   Example: 9(tab) becomes \x9 or alternatively use \t.

Hope this will help.

Linebreeding

There is a built in for escaping a regex string between delimiters php.net/manual/en/function.preg-quote.php – Handcraft

Answer 3

delimiters, add any char to beginning and end of expression, in this case, and by tradition, the '/' character preg_replace('/.*\.(.*)$/',"\\1",$imgfile); The regex isn't very good, better to use strrpos and take substr().

Regex is slow, use this. $extension=substr($imgName,strrpos($imgName,'.'));

Christan

I know but having this problem; preg_replace() [function.preg-replace]: Unknown modifier '$' in C:\wamp\www.. – Lemuel

Yes, my bad, also the editing seems to destroy the expression. In the end better to use a substr() in this case. You could also use preg_match. – Christan

You can escape your code with backticks (see stackoverflow.com/editing-help). The $ fix looks good. – Devon