Delimiter must not be alphanumeric or backslash and preg match

Question

I have this code     string1    My name is  Kate  and im fine     pattern    My name is        and im fine    preg match  pattern    string1   matches   echo  matches 1     and when im run it returns this error      Warning  preg match    function preg-match   Delimiter must not be alphanumeric or backslash

User · Answer

You must specify a delimiter for your expression. A delimiter is a special character used at the start and end of your expression to denote which part is the expression. This allows you to use modifiers and the interpreter to know which is an expression and which are modifiers. As the error message states, the delimiter cannot be a backslash because the backslash is the escape character.

$pattern = "/My name is '(.*)' and im fine/";

and below the same example but with the i modifier to match without being case sensitive.

$pattern = "/My name is '(.*)' and im fine/i";

As you can see, the i is outside of the slashes and therefore is interpreted as a modifier.

Also bear in mind that if you use a forward slash character (/) as a delimiter you must then escape further uses of / in the regular expression, if present.

User · Answer

The solution  which other answers don t mention mdash at least at the time of my originally writing this  is that when PHP refers to delimiters  it s not referring to the delimiters you see in your code  which are quote marks  but the next characters inside the string    In fact I ve never seen this stated anywhere in any documentation  you have to see it in examples    So instead of having a regular expression syntax like what you may be accustomed to from many other languages    something    PHP uses strings  and then looks inside the string for another delimiter     something     The delimiter PHP is referring to is the pair of   characters  instead of the pair of   characters   So if you write  something   PHP will take s as the intended delimiter and complain that you re not allowed to use alphanumeric characters as your delimiter   So if you want to pass  for instance  an i to show that you want a case-insensitve match  you pass it inside the string but outside of the regex delimiters     something i    If you want to use something other than   as your delimiter  you can  such as if you re matching a URL and don t want to have to escape all the slashes     something

User · Answer

You can also use T-Regx library which has automatic delimiters for you    matches   pattern  My name is        and im fine  - gt match  string1 - gt all                           No delimiters needed

User · Answer

Please try with this       pattern     My name is          and im fine

User · Answer

The pattern must have delimiters  Delimiters can be a forward slash     or any non alphanumeric characters             Examples    pattern     My name is        and im fine      pattern     My name is        and im fine     pattern     My name is        and im fine

User · Answer

Maybe not related to original code example  but I received the error  Delimiter must not be alphanumeric or backslash  and Googled here  Reason  I mixed order of parameters for preg match  Pattern was the second parameter and string to match was first  Be careful

User · Answer

You need a delimiter for your pattern   It should be added at the start and end of the pattern like so    pattern     My name is        and im fine        With   as a delimeter

[php] Delimiter must not be alphanumeric or backslash and preg_match

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