3.5. Test If a Match Can Be Found Within a Subject String
Problem
You want to check whether a match can be found for a particular
regular expression in a particular string. A partial match is
sufficient. For instance, the regex ‹regex●pattern
› partially matches The regex pattern can be
found
. You don’t care about any of the details of the match.
You just want to know whether the regex matches the string.
Solution
C#
For quick one-off tests, you can use the static call:
bool foundMatch = Regex.IsMatch(subjectString, "regex pattern
");
If the regex is provided by the end user, you should use the static call with full exception handling:
bool foundMatch = false; try { foundMatch = Regex.IsMatch(subjectString, UserInput); } catch (ArgumentNullException ex) { // Cannot pass null as the regular expression or subject string } catch (ArgumentException ex) { // Syntax error in the regular expression }
To use the same regex repeatedly, construct a Regex
object:
Regex regexObj = new Regex("regex pattern
");
bool foundMatch = regexObj.IsMatch(subjectString);
If the regex is provided by the end user, you should use the
Regex
object with full
exception handling:
bool foundMatch = false; try { Regex regexObj = new Regex(UserInput); try { foundMatch = regexObj.IsMatch(subjectString); } catch (ArgumentNullException ex) { // Cannot pass null as the regular expression or subject string } } catch (ArgumentException ex) { // Syntax error in the regular expression }
VB.NET
For quick one-off tests, you can use the static ...
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