Using regular expressions
In typical search and replacement operations, the exact text to be found must be provided. This technique may be sufficient for simple search and replacement tasks in static text, but due to its lack of flexibility, it is difficult or even impossible to search for dynamic text.
Using regular expressions, you can:
- Tests a pattern of a string. For example, you can test an input string to see if there is a phone number pattern or a credit card number pattern in the string. This is called data validation.
- Replace text. You can use a regular expression in a document to identify a specific text, and then you can delete it all, or replace it with another text.
- Extract a substring from the string according to pattern matching. Can be used to find specific text in text or input fields.
For example, if you need to search the entire web site to remove some outdated material and replace some HTML formatting tags, you can test each file using regular expressions to see if the material or HTML formatting tags are present in that file. This method allows you to narrow the affected files to those files containing the material you want to delete or change. Then you can use regular expressions to remove outdated materials, and finally, you can use regular expressions again to find and replace those tags that need to be replaced.
Another example that illustrates that regular expressions are very useful is a language whose string processing power is not yet known. VBScript is a subset of Visual Basic that has rich string processing capabilities. Visual Basic Scripting Edition similar to C does not have this capability. Regular expressions have brought significant improvements to the string processing capabilities of Visual Basic Scripting Edition. However, it may be more efficient to use regular expressions in VBScript, which allows multiple string operations to be performed in a single expression.