Need Coding explained

netfrugal

Can someone help explain the first part of this:

ereg_replace("[ ()-]+", "", $row['phone'])

I understand what it's doing from the outcome, but I don't quite understand what this means:

"[ ()-]+"

I've been searching for some explanation, but get more info that doesn't quite help me out.

Anyone know a site that explains what the brackets, minus sign, plus sign, and anything else mean? There seems to be a logic how to place it all too!

thanks!

sheephat

http://uk.php.net/manual/en/function.ereg-replace.php

its simply removing the characters [ ] ( ) - +.

Weedpacket

netfrugal wrote:
There seems to be a logic how to place it all too!

There'd have to be, otherwise no-one would be able to get a computer to understand it.

NogDog

The "[" and "]" delineate a character class, which will match on any of the characters contained within it. So it is matching any character that is a space, "(", ")", or "-". The "+" after the character class is a repetition modifier which means to match on 1 or more occurrences of the preceding character or sub-pattern, so in this case it means match on 1 or more successive occurrences of any of those 4 characters defined in that character class, and then replace them all with an empty string.

netfrugal

What I mean, is I'm trying to understand the logic to the first parameter.

From what I see, it's not taking out the brackets, but you put the items you wish to replace [inside the brackets]

[ ()-]+ means to look for parentheses and the dash. But the + plus isn't affected. That must mean I can add more to replace?

I already took a look at the PHP explaination of ereg_replace. But it doesn't go into detail of explaining all this.

<?
$text = ereg_replace("[ ()-]+", " ", "555-555-5(a)55+5[]");

echo $text;
?>

outputs: 555 555 5 a 55+5[]

And what if I want to add more, like taking out letters, or other characters to replace?

laserlight

You need to search the Web for a regular expression tutorial, and also read the PHP manual on PCRE.

[ ()-]+ means to look for parentheses and the dash. But the + plus isn't affected. That must mean I can add more to replace?

[ ()-] means "match a space, an opening parenthesis, a closing parenthesis, or a dash". x+ means "match x one or more times". So [ ()-] means "match one or more spaces, opening parentheses, closing parentheses, or dashes".

I already took a look at the PHP explaination of ereg_replace. But it doesn't go into detail of explaining all this.

Do not use the ereg family of regular expression functions. Use the PCRE functions instead, in this case [man]preg_replace/man. The syntax is similiar, but of course you still need to read up on regular expressions yourself.

NogDog

If you want to specify square brackets within a character class, then you need to escape them:

"[ ()\-\[\]]+"

(Hyphens also need to be escaped if they are not to represent a range of characters, or are obviously not part of such a range as when they are the last character in a character class.)

laserlight

Incidentally, I suggest using single quote delimited strings for regex patterns. Using double quotes can cause PHP's special characters to interfere with the regex.