Sujit Kumar Shah

The regular expression, as a pattern, can match all kinds of text strings helping your application validate, compare, compute, decide etc. It can do simple or very complex string manipulations. The list of possibilities is enormous when it comes to what you can achieve using regular expressions. You can take any phrase that starts with an "A" or any A - Z character and do various things with it. You can match phone numbers, email addresses, URL, credit card numbers, social security numbers, zip codes, states, cities.....(the list never ends). A huge script that is supposed to validate a user input and prepare it for SQL can be reduced to only one line with the help of preg_replace.

You can see the Google search results and many other sites that have good search functionality. When you perform a search, your words or phrases are highlighted in the search results making it easy to find out the most relevant content.

From this page today I'm going to show you a simple way to searching and replacing on.

The CAPTCHA  is a very very useful test to prevent abuse on the websites. When you create a web form like registration, login, contact us, blog comment etc..., We are suffering day by day with unwanted email or web spam abuse. So if you use CAPTCHA on your website forms, this can help in stopping Guestbook Spam, Blog Spam, Wiki Spam, Comment Spam, Feedback Form Spam, Other Types of Web Form Spam.

The goal of this tutorial is to demonstrate how to make your own simple CAPTCHA protection using PHP. For this we needed to enabled gd library, you can create a captcha code for your registration form or any web forms using PHP.

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