Tham khảo tài liệu 'professional information technology-programming book part 94', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Who Is Sams Teach Yourself Regular Expressions For This book is for you if You are new to regular expressions. You want to quickly learn how to get the most out of the regular expression language. You want to gain an edge by learning to solve real problems using one of the most powerful and least understood tools available to you. You build Web applications and crave more sophisticated form and text processing. You use Perl ASP Visual Basic .NET C Java JSP PHP ColdFusion and many other languages and you want to learn how to use regular expressions within your own application development. You want to be productive quickly and easily in regular expressions without having to call someone for help. Lesson 1. Introducing Regular Expressions In this lesson you ll learn what regular expressions are and what they can do for you. Understanding the Need Regular expressions or regex for short are tools and like all tools regular expressions are designed to solve a very specific problem. The best way to understand regular expressions and what they do is to understand the problem they solve. Consider the following scenarios You are searching for a file containing the text car regardless of case but do not want to also locate car in the middle of a word for example scar carry and incarcerate . You are generating a Web page dynamically using an application server and need to display text retrieved from a database. Text may contain URLs and you want those URLs to be clickable in the generated page so that instead of generating just text you generate a valid HTML A HREF A . You create a Web page containing a form. The form prompts for user information including an email address. You need to verify that specified addresses are formatted correctly that they are syntactically valid . You are editing a source code and need to replace all occurrences of size with iSize but only size and not size as part of another word. You are displaying a list of all files in your computer file system
