Application of the positive expression of ASP (I.)

The application of regular expressions
How to implement the paging display of data records

Application of regular Expressions (author: Tommy)
I. Overview of regular expressions
The application of regular expression in VBScript
The application of regular expression in Vavascript
Iv. examples
V. Summary
I. Overview of regular expressions
If you have not used regular expressions before, you may not be familiar with this term or concept. However, they are not as novel as you might think.
Recall how you found the file on your hard disk. Are you sure you will use it? and * characters to help find the file you are looking for. The character matches a single character in the file name, while the * matches one or more characters. One like ' data?. DAT ' mode can be found in the following files: Data1.dat, Data2.dat and so on. If you use the * character instead? Character, the number of files found will be enlarged. ' Data*.dat ' can match all of the following file names: Data.dat, Data1.dat, Data12.dat, and so on, although this method of searching for files is certainly useful but very limited. and * The limited ability of wildcards allows you to have a concept of what regular expressions can do, but regular expressions are more powerful and flexible.
When we write ASP programs, we often judge the validity of a string, such as whether a string is a number, whether it is a valid email address, and so on. If you do not use regular expressions, then the judgment of the program will be very long and error prone, if the use of regular expressions, these judgments is a very easy job. Later we will describe how to determine the validity of digital and email addresses.
In a typical search and replace operation, you must provide the exact text you want to find. This technique may be sufficient for simple search and replace tasks in static text, but because of its lack of flexibility, it is difficult or even impossible to search for dynamic text.
What can be done with regular expressions?
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 known as data validation.
Replaces text. You can use a regular expression in your document to identify specific text, and then you can delete it all, or replace it with another text.
Extracts a substring from a string based on 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 use regular expressions to test each file to see if there are any material or HTML formatting tags that you want to find in the file. With this method, you can narrow the affected file range to those files that contain the material you want to delete or change. You can then use regular expressions to delete obsolete materials, and finally, you can use regular expressions again to find and replace those that need to be replaced.