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I use this condition to check if the value is alphanumeric values:
$value =~ /^[a-zA-Z0-9]+$/
How can I modify this regex to account for a possible dot . in the value without accepting any other special characters?
994
The dot in regular expressionsThe dot essentially matches any character. For example, the following expression means "a digit plus any other character": [0-9]. Really, this expression means "any number (including zero) of any character, followed by twn digits, followed by any number of any character".
In regular expressions, the dot or period is one of the most commonly used metacharacters. Unfortunately, it is also the most commonly misused metacharacter. The dot matches a single character, without caring what that character is. The only exception are line break characters.
Regular Expression (Regex or Regexp or RE) in Perl is a special text string for describing a search pattern within a given text. Regex in Perl is linked to the host language and is not the same as in PHP, Python, etc. Sometimes it is termed as “Perl 5 Compatible Regular Expressions“.
(dot) metacharacter, and can match any single character (letter, digit, whitespace, everything). You may notice that this actually overrides the matching of the period character, so in order to specifically match a period, you need to escape the dot by using a slash \.
$value =~ /^[a-zA-Z0-9.]+$/
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