Why Does `preg_match` Throw a 'Delimiter Must Not Be Alphanumeric or Backslash' Error?

'Delimiter must not be alphanumeric or backslash' Error in preg_match

While attempting to use the preg_match function with a pattern, you may encounter the error "Delimiter must not be alphanumeric or backslash." This error indicates that the delimiter used in the pattern is not valid.

A delimiter is a character that separates the pattern from the rest of the string. In the provided code snippet, the pattern is defined as "$pattern = "My name is '(.*)' and im fine"". The delimiter used here is the double quotes ("") which is invalid.

Resolving the Error

To resolve this error, you need to specify a valid delimiter for the pattern. A valid delimiter can be any non-alphanumeric character and backslash (). Commonly used delimiters include forward slash (/), pound sign (#), and pipe symbol (|).

Example

In this example, we will use forward slash as the delimiter:

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

This pattern now has a valid delimiter and should work properly when used with the preg_match function.

Importance of Delimeters

Delimiters are crucial in regular expressions as they separate the pattern from the rest of the string. Without a proper delimiter, the regular expression engine would not know where the pattern ends and where the text begins. This can lead to unexpected results or errors.

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