PHP: ereg - Manual

Description

int ereg ( string pattern, string string [, array &regs] )

Note: preg_match(), which uses a Perl-compatible regular expression syntax, is often a faster alternative to ereg().

Searches a string for matches to the regular expression given in pattern in a case-sensitive way.

If matches are found for parenthesized substrings of pattern and the function is called with the third argument regs, the matches will be stored in the elements of the array regs. $regs[1] will contain the substring which starts at the first left parenthesis; $regs[2] will contain the substring starting at the second, and so on. $regs[0] will contain a copy of the complete string matched.

Note: Up to (and including) PHP 4.1.0 $regs will be filled with exactly ten elements, even though more or fewer than ten parenthesized substrings may actually have matched. This has no effect on ereg()'s ability to match more substrings. If no matches are found, $regs will not be altered by ereg().

Returns the length of the matched string if a match for pattern was found in string, or FALSE if no matches were found or an error occurred. If the optional parameter regs was not passed or the length of the matched string is 0, this function returns 1.

The following code snippet takes a date in ISO format (YYYY-MM-DD) and prints it in DD.MM.YYYY format:

Example 1. ereg() example

<?php 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"; } ?>

User Contributed Notes
ereg

berndt at michael berndt dot de
29-Apr-2005 08:23


extract various array elements with ereg()

http://www.michael-berndt.de/ie/tux/BerndtSector.htm

php at REMOVEMEkennel17 dot co dot uk
26-Apr-2005 09:00


After a lot of hard work I managed to create the following regular expression, which matches any HTML tag pair (i.e. opening and closing tag), as specified by tagname:



^(.*)(<[ \n\r\t]*tagname(>|[^>]*>))(.*)(<[ \n\r\t]*/[ \n\r\t]*tagname(>|[^>]*>))(.*)$



The expression is deliberately very forgiving of bad HTML - I wanted to match anything that could be reasonably accepted by a forgiving browser, rather than make it standards compliant. Whitespace is allowed between the tagname and the opening and closing tag symbols, and also between the / and the tagname for the closing tag.



For my own use, I have wrapped it in a function call, which you may find useful.  Here it is with a few notes. I hope somebody finds it useful.



- Mark Clements



<?php 



function ereg_MatchedHTMLTags($tagname) {

    return "^(.*)(<[ \\n\\r\\t]*$tagname(>|[^>]*>))(.*)(<[ \\n\\r\\t]*/[ \\n\\r\\t]*$tagname(>|[^>]*>))(.*)$";

}



// Use with eregi to ensure case-insensitive match.

//        e.g. to split an HTML page based on body tag: 

//             eregi(ereg_MatchedHTMLTags('body'), $Source, $Matches) 



// The following values will be held in $Matches

//(marked values are unintended byproducts of the expression)

//           *[0] - the entire string ($Source).

//            [1] - everything before the opening tag

//            [2] - the opening tag, including all contents (i.e. everything between < and >)

//           *[3] - the opening tag from end of the tag name, 

//                      e.g. '<body bgcolor="#000000">' gives ' bgcolor="#000000">'

//            [4] - the tag contents (everything between the opening and closing tag)

//            [5] - the complete closing tag.

//           *[6] - the closing tag from the end of the tag name

//                      e.g. '</body invalid text>' gives ' invalid text>'

//            [7] - everything after the closing tag.



?>

kitchen -at- script kitchen -dot- com
08-Apr-2005 08:52


just to note here, php4's ereg() doesn't support [:space:], so if you want to match arbitrary whitespace, use preg_match()



$string = "hi \t  bob";



if (ereg("hi[:space:]*bob", $string)) {

 print "you must be using php5!\n";

}



// php4 version



if (preg_match("/hi\s*bob/",$string)) {

 print "works in both php4 and php5!\n";

}



php5's ereg() does support [:space:]

alcator at seznam dot cz
11-Mar-2005 01:47


Reaction to:



(19[0-9]{2}|20[0-5]{2})-(0[0-9]|1[0-2])-([12][0-9]|3[01])



--> There is more problems than just "this will validate 2005-02-31". The worse problem is that it WON'T validate 2001-01-01...



(19[0-9]{2}|200[0-5]{1})-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])



(Note that "00" is no longer possible for days and months, while allowing for 01..09...)



Still, it doesn't protect against non-existent dates.

Candle1deleteme2121 at DELETEMEhotmail dot com
07-Mar-2005 05:36


remember that putting an invalid date such as 2005-02-31 through mktime() http://uk2.php.net/manual/en/function.mktime.php you end up with a correct date, the above example would end up as 2005-03-03 (on a non-leap year)

LIX
01-Mar-2005 04:13


It's important to know - when you use

[0-9]{4})-([0-9]{2})-([0-9]{2} 

to valid date in YYYY-MM-DD format then script accepts dates etc. 20005-02-035



You can use 

^[0-9]{4})-([0-9]{2})-([0-9]{2}$ 

to valid regular date format YYYY-MM-DD.

24-Feb-2005 02:17


The date example above is still a little dodgey as this:



(19[0-9]{2}|20[0-5]{2})-(0[0-9]|1[0-2])-([12][0-9]|3[01])



will allow invalid dates such as 



1900-00-31



Just a small correction is needed (IMO), switching a 0 for a 1:



(19[0-9]{2}|20[0-5]{2})-(0[1-9]|1[0-2])-([12][0-9]|3[01])

                                       ^ 

Of course invalid dates such as 31st feb are still possible.

punkpuke at comcast dot net
15-Feb-2005 06:02


This took me a little to find out, but from one PHP/Regex newb to another if your trying to let people use Square Brackets in a string:   [  ]



Like in this string for example: ^[a-zA-Z0-9]{1,}$



This following will most likely not work (You can't backslash them): ^[a-zA-Z0-9\[\]]{1,}$



So, to escape the Square Brackets, use the following to delimit collating symbols:



[. Special Character Goes Here  .]



So The New Expression:  ^[a-zA-Z0-9 [.[.] [.].] ]{1,}$ (I spaced it so it was less confusing)

rhondle at hotmail dot com
13-Feb-2005 05:56


In addition to validating a date string with a regular expression, it would be a good idea to test it's validity using PHP's checkdate() function.



http://www.php.net/manual/en/function.checkdate.php

Carrajola
12-Feb-2005 12:54


Since the example has the purpose of validating the date in $date and not just change it, the regular expression is not accurate, because a date like 0000-00-00 is validated. 



It should be something like this:



(19[0-9]{2}|20[0-5]{2})-(0[0-9]|1[0-2])-([12][0-9]|3[01])



this regular expression is still not totally correct because it's not sensible to a impossible date like 2005-02-31.