3.3. Create Regular Expression Objects
Problem
You want to instantiate a regular expression object or otherwise compile a regular expression so you can use it efficiently throughout your application.
Solution
C#
If you know the regex to be correct:
Regex regexObj = new Regex("regex pattern");If the regex is provided by the end user (UserInput being a string
variable):
try {
Regex regexObj = new Regex(UserInput);
} catch (ArgumentException ex) {
// Syntax error in the regular expression
}VB.NET
If you know the regex to be correct:
Dim RegexObj As New Regex("regex pattern")If the regex is provided by the end user (UserInput being a string
variable):
Try
Dim RegexObj As New Regex(UserInput)
Catch ex As ArgumentException
'Syntax error in the regular expression
End TryJava
If you know the regex to be correct:
Pattern regex = Pattern.compile("regex pattern");If the regex is provided by the end user (userInput being a string
variable):
try {
Pattern regex = Pattern.compile(userInput);
} catch (PatternSyntaxException ex) {
// Syntax error in the regular expression
}To be able to use the regex on a string, create a Matcher:
Matcher regexMatcher = regex.matcher(subjectString);
To use the regex on another string, you can create a new
Matcher,
as just shown, or reuse an existing one:
regexMatcher.reset(anotherSubjectString);
JavaScript
Literal regular expression in your code:
var myregexp = /regex pattern/;Regular expression retrieved from user input, as a string stored
in the variable userinput:
var myregexp ...