Learning regular expressions

rokchik

This book (php4, unfortunately) is trying to teach me about regular expressions.
I typed the following:

$str = "Hello, this <b>word</b> is bold!";
if (ereg("<([[:alnum:]]+)>([^<])*</\\1>"),$str,$Pockets) {
	echo "The '$Pockets[2]' word is enclosed in '<$Pockets[1]>' tags";
	}

I get the error msg: Parse error: syntax error, unexpected ',' in the line with the regex in it.

All help will be appreciated.
TIA.

bradgrafelman

Eh, if the book you're reading is old enough to be focused on PHP4 and use the ereg*() functions, then I honestly think it's time to throw away the book and get a new one.

The problem in your code (besides the fact that you're using the long since deprecated ereg() functions) is that you're missing a ')' to close the if() statement.

laserlight

I suggest reading the PHP manual on PCRE instead. It should be preferred to the ereg() type functions.

rokchik

bradgrafelman wrote:
Eh, if the book you're reading is old enough to be focused on PHP4 and use the ereg*() functions, then I honestly think it's time to throw away the book and get a new one.

The problem in your code (besides the fact that you're using the long since deprecated ereg() functions) is that you're missing a ')' to close the if() statement.

Thank you. I thought it was something like that as I found a ';' at the end of the if() instead of {...} ...

Now, either I've been typing for too long or this book has a serious misprint. 😕 Where exactly should that ')' go, please?

EDIT: Yes, I know, the book has worn out its last legs. I'm hoping for a new one for my birthday, so I'm learning what I can lay my hands on til then.

Thanks

bradgrafelman

The ')' you're missing is the one closing the if() statement. This line:

if (ereg("<([[:alnum:]]+)>([^<])*</\\1>"),$str,$Pockets) {

(ignoring the data inside the regular expression pattern string) has two ('s but only one ), thus the ereg() function is closed, but the if() statement doesn't have a closing ')' on the end of it.

NogDog

bradgrafelman wrote:
The ')' you're missing is the one closing the if() statement. This line:
if (ereg("<([[:alnum:]]+)>([^<])*</\\1>"),$str,$Pockets) { 
(ignoring the data inside the regular expression pattern string) has two ('s but only one ), thus the ereg() function is closed, but the if() statement doesn't have a closing ')' on the end of it.

Which is probably my most common parse error (ignoring plain old "fat-fingerning" typos). 🙂

rokchik

Yes, I found that too after a while, but it still wouldn't work. I tested the following, which I borrowed from php.net for demo purposes;

if (ereg ("([0-9]{4})-([0-9]{1,2})-([0-9]{1,2})", $date, $regs)) {
    echo "$regs[3].$regs[2].$regs[1]";
} else {
    echo "Invalid date format: $date";
}

That didn't work either, even if I fed it a date. But ereg works if it's not a condition of an if() statement. It works happily on its own or as the result of a function.

Thanks very much for your help.
Much appreciated.
Rokchik

bradgrafelman

Your code worked fine for me... this:

<?php
$date = "2004-02-07";
if (ereg ("([0-9]{4})-([0-9]{1,2})-([0-9]{1,2})", $date, $regs)) {
    echo "$regs[3].$regs[2].$regs[1]";
} else {
    echo "Invalid date format: $date";
} 
?>

outputted this:

07.02.2004

EDIT: As a side note, you could convert this to use the [man]PCRE[/man] functions quite easily:

if (preg_match("/([0-9]{4})-([0-9]{1,2})-([0-9]{1,2})/", $date, $regs)) {

Also note that if you're getting the dates from a database (e.g. MySQL), then it would be simpler (and more efficient, I'd think) to use MySQL's built-in function DATE_FORMAT().