VBS Tutorial: Introduction to regular expressions-use regular expressions

Use Regular Expressions

In typical search and replacement operations, you must provide the exact text to be searched. This technology may be sufficient for simple search and replacement tasks in static text, but it is difficult or even impossible to search dynamic text due to its lack of flexibility.

With a regular expression, you can:

• Test a mode of a string. For example, you can test an input string to see if there is a phone number or a credit card number. This is called Data Validity verification.
• Replace text. You can use a regular expression in a document to identify a specific text, and then delete it all or replace it with another text.
• Extract a substring from the string based on the pattern match. It can be used to search for specific text in text or input fields.

For example, if you need to search the entire web site to delete outdated materials and replace some HTML formatting tags, you can use a regular expression to test each file, check whether there are materials or HTML formatting tags in the file. With this method, you can narrow down the affected files to the files that contain the materials to be deleted or changed. Then, you can use a regular expression to delete outdated materials. Finally, you can use a regular expression to find and replace the tags that need to be replaced.

Another example that describes the usefulness of regular expressions is a language with unknown string processing capabilities. VBScript is a subset of Visual Basic and has rich string processing functions. Visual Basic Scripting Edition similar to C does not have this capability. Regular Expressions significantly improve the string processing capability of Visual Basic Scripting Edition. However, it may be more efficient to use regular expressions in VBScript. It allows multiple string operations in a single expression.