As you working in any project regular expressions are very usefull to Form Validation,
here is some of Regular expression which is frequently used for form validation:

here is some of Regular expression which is frequently used for form validation:

- Email Validation
- Mobile/Phone Number validation
- Strong Password validation
- IP Address Validation
- Uploaded Image File Validation
<?php // Valid Email Address Number or Not $email="master@example.com"; if(preg_match('/([\w-\.]+)@((?:[\w]+\.)+)([a-zA-Z]{2,4})/',$email)) { echo "<br>Valid Email Address"; }else { echo "<br>Invalid "; } // Valid Phone Number or Not $phone="434-333-4454"; if(preg_match('/[(]?\d{3}[)]?\s?-?\s?\d{3}\s?-?\s?\d{4}/',$phone)) { echo "<br>Valid Phone Number"; }else { echo "<br>Invalid Phone Number"; } // Valid Strong Password or Not (Check password with Digits Caps Small Letters symols ) $password="A4z#s3"; if(preg_match('/(?!^[0-9]*$)(?!^[a-zA-Z!@#$%^&*()_+=<>?]*$)^([a-zA-Z!@#$%^&*()_+=<>?0-9]{6,15})$/',$password)) { echo "<br>Strong Password"; }else { echo "<br>Weak Password"; } // Valid IPv4 Address or Not 0.0.0.0 to 255.255.255.255 $ipaddress="128.222.234.182"; if(preg_match('/\b[12]{1}(?(?<=2)[0-5]|[0-9])?(?(?<=25)[0-5]|[0-9])?\.[12]?(?(?<=2)[0-5]|[0-9])?(?(?<=25)[0-5]|[0-9])?\.[12]?(?(?<=2)[0-5]|[0-9])?(?(?<=25)[0-5]|[0-9])?\.[12]{1}(?(?<=2)[0-5]|[0-9])?(?(?<=25)[0-5]|[0-9])?\b/',$ipaddress)) { echo "<br>Valid IP Address"; }else { echo "<br>Invalid IP Address"; } // Valid Image or Not (jpg|gif|png) $imagefile="mypicture.jpg"; if(preg_match("/^[a-zA-Z0-9-_\.]+\.(jpg|gif|png)$/",$imagefile)) { echo "<br>Valid Image file"; }else { echo "<br>Invalid Image file"; } ?>