CODEWITHSUNDEEP
phpregex
Saturn
Saturn

Reputation: 65

How can I match the number of characters in RegEx exactly in this situation?

$db = new PDO($dsn, $db_id, $dbpw);
$db= new PDO($dsn, $db_id, $dbpw);

I want to get exactly the variable name '$db'.

Other variable names starting with $db should be excluded.

I wrote the following regular expression:

/(\$db)[^_a-zA-Z0-9]/g

So '$db_id' and '$dbpw' were excluded as I intended.

However, just to the right of $db, one character(space, =, etc.) is matched 'more' like this: '$db ', '$db='

This is not my intention. How can I match exactly '$db' in this situation?

Upvotes: 1

Views: 46

Answers (1)

falsetru
falsetru

Reputation: 368894

You can use word boundary (\b):

/(\$db)\b/

According to Regex Tutorial - \b Word Boundaries:

There are three different positions that qualify as word boundaries:

  • Before the first character in the string, if the first character is a word character.
  • After the last character in the string, if the last character is a word character.
  • Between two characters in the string, where one is a word character and the other is not a word character.

Simply put: \b allows you to perform a "whole words only" search using a regular expression in the form of \bword\b. A "word character" is a character that can be used to form words. All characters that are not "word characters" are "non-word characters".

Upvotes: 1

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