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php pcre regular expressions without delimiter

Hey everyone,

I've been working with PHP and I recently came across something called PCRE (Perl Compatible Regular Expressions). I understand the basics of regular expressions, but there's one thing I'm finding a bit confusing.

I've seen examples where PCRE regular expressions are used without a delimiter. From what I understand, in PHP, we usually enclose regular expressions between delimiters such as forward slashes (/). However, in these examples, there were no delimiters used.

I'm wondering how this works. Can someone please explain to me how PCRE regular expressions can be written without delimiters? Are there any specific rules or syntax I need to follow when using PCRE without delimiters?

I appreciate any insights or examples you might have to help me understand this concept better. Thank you in advance!

All Replies



I've actually encountered this situation before and can share my personal experience with PCRE regular expressions without delimiters.

In some cases, you can use a specific character as a delimiter instead of the traditional forward slash (/) delimiter. This is often done when the regular expression itself contains forward slashes, making it difficult to define clear boundaries.

For instance, consider a scenario where you want to match a URL that contains a forward slash (/) in it. Instead of the usual pattern `/\/somepattern\//`, you can use a different delimiter, such as the hash symbol (#), like `#\/somepattern\/#`. This approach allows you to avoid escaping the forward slashes within the pattern itself.

However, it's important to keep in mind that when using an alternate delimiter, it should be consistent throughout the expression. So, if you choose the hash symbol as the delimiter, you should use it at the beginning and end of your pattern. Additionally, you should escape the chosen delimiter if it appears in the pattern itself.

I hope this helps clarify things a bit. If anyone else has additional tips or insights on using PCRE regular expressions without delimiters, feel free to chime in!


Hey there,

I've been working with PHP and PCRE for quite some time now, and I can share my personal experience regarding the use of PCRE regular expressions without delimiters.

In certain scenarios, omitting the delimiters can be handy when you're dealing with complex regular expressions. I've found that it helps make the patterns more readable and avoids cluttering the expression with additional delimiter characters.

To use PCRE without delimiters, you need to enclose the pattern in parentheses instead. For example, instead of using the pattern `/\bword\b/`, you can write it as `(\bword\b)`. The parentheses here act as the delimiters, allowing the pattern to be parsed correctly.

Do note, though, that omitting the delimiters also means that you won't be able to specify any modifiers, such as case-insensitive matching or global matching. If you require any modifiers, it's best to stick with the traditional delimiter-based syntax.

I hope my experience clears up any confusion and helps you in using PCRE regular expressions without delimiters. If you have any further questions or if anyone has different insights on this, feel free to share!



I've never personally encountered the use of PCRE regular expressions without delimiters, but I did come across some information that might be helpful in understanding this concept.

From my research, I found that PCRE allows for alternative delimiters to be used, giving you more flexibility in defining your regular expressions. Instead of using traditional delimiters like forward slashes (/), you can choose other characters like tildes (~), at signs (@), or exclamation marks (!) as delimiters.

Using different delimiters can be especially useful when your regular expression contains a lot of forward slashes, as it helps avoid excessive escaping. It can make your expressions more readable and easier to work with.

Just bear in mind that if you opt for an alternative delimiter, make sure to use it consistently throughout your pattern. Also, remember to escape the chosen delimiter character if it appears in the expression itself.

While I haven't personally used PCRE without delimiters, I hope this information sheds some light on the topic. If anyone else has first-hand experience or additional insights, please share your thoughts!

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