Php Development » regular expressions

60 validation functions with php 2 part

mahesh chari — Fri, 04 Feb 2011 07:01:07 +0000

This is second part of 60 PHP validation functions.

PHP validation functions

Validation for Javascript injection (jssafe)

Use: There is a chance to hackers to include javascript code in our Input form elements such as Text area ,Text element.It is best practice to avoid such hacking in E-commerce applications.

Javascript Script Regular Expression

/<script[^>]*>[\s\r\n]*(<\!--)?|(-->)?[\s\r\n]*<\/script>/

PHP function

  /**
  * Check given sting has script tags
  * @param   string   
  * @return  boolean
  */
  function is_jssafe($val)
  {
  return (bool)(!preg_match("/]*>[\s\r\n]*(<\!--)?|(-->)?[\s\r\n]*<\/script>/",
  $val));
 
  }

Validation for String length

Use: validate string length.

Regular Expression

We used handy PHP functions here

PHP function

  /**
  * check for exactly length of string
  * @param   string  
  * @return  boolean
  */
  function is_length($val, $length)
  {
  return (strlen($val) == (int)$length);
 
  }

Validation for lower case String

Use: Oops! in my experiance i didn’t got a chance to validate againest this. But i kept for reference cause it may use full to any one.

Regular Expression

/^[a-z]+$/

PHP function

  /**
  * Given sting is lower cased
  * @param   string   
  * @return  boolean
  */
  function is_lower($val)
  {
  return (bool)preg_match("/^[a-z]+$/", $val);
 
  }

Validate macaddress

Use: In some network related and secure money transfer application ,it best practice to rely on MacAddress than IP address. This can be captured with JAVA applet only

Mac address Regular Expression

/^([0-9a-fA-F][0-9a-fA-F]:){5}([0-9a-fA-F][0-9a-fA-F])$/

PHP function

  /**
  * Checks given value again MAC address of the computer
  * @param   string   value      
  * @return  boolean
  */
  function is_macaddress($val)
  {
  return (bool)preg_match('/^([0-9a-fA-F][0-9a-fA-F]:){5}([0-9a-fA-F][0-9a-fA-F])$/',
  $val);
  }

Validation for strict Object matches

Use: It is used in DB session handling , we fetch object from serialized input from files, Database ..etc. when unserialise it best practice to validate that object .

Regular Expression

We use PHp comparision

PHP function

  /**
  * compares two any kind of values ,stictly
  * @param   string   
  * @return  boolean
  */
  function is_matches($val, $value)
  {
  return ($val === $value);
 
  }

Validation for String lenght maximum

Use: in mostly forms we must validate the input value for maximum length, cause Mysql VARACHAR(255) supports.

Regular Expression

We use PHP comparision

PHP function

  /**
  * check string length exceeds maximum length     
  * @param   string   
  * @return  boolean
  */
  function is_maxlength($val, $max)
  {
  return (strlen($val) <= (int)$max);
  }

Validation for number maximum value

Use: It is most common validation againest numbers

Regular Expression

We use PHP comparision

PHP function

  /**
  * check given number exceeds max values   
  * @param   string   
  * @return  boolean
  */
  function is_maxvalue($number,$max)
  {
  return ($number >$max);
 
  }

Validate md5 String

Use: in mostly case we use md5 for secret data passing and key , password validation.

md5 string Regular Expression

/[0-9a-f]{32}/i

PHP function

  /**
  * Checks that a field matches a v2 md5 string
  * @param   string   
  * @return  boolean
  */
  function is_md5($val)
  {
  return (bool)preg_match("/[0-9a-f]{32}/i", $val);
 
  }

Validation for String minimum length

Use: in mostly forms we must validate the input value for maximum length, cause Mysql VARACHAR(255) supports.

PHP function

  /**
  *Check the string length has minimum length
  * @param   string   
  * @return  boolean
  */
  function is_minlength($val, $min)
  {
  return (strlen($val) >= (int)$min);
 
  }

Validation for number minimum value

Use : mostly forms elements we check this validation, example in registration form we ask user age.

Regular Expression

We use PHP comparision

PHP function

  /**
  * check given number below value   
  * @param   string   
  * @return  boolean
  */
  function is_minvalue($number)
  {
  return ($number < $max);
 
  }

Validation for multy line characters.

Use: some times ,we need to strip or validate the new line characters.

Regular Expression

/[\n\r\t]+/

PHP function

  /**
  * check given sring has multilines 
  * @param   string   
  * @return  boolean
  */
  function is_multiline($val)
  {
  return (bool)preg_match("/[\n\r\t]+/", $val);
 
  }

Validation for numeric

Use: validate given input string is numeric with optional +,-,. values

Regular Expression

/^[\-+]?[0-9]*\.?[0-9]+$/

PHP function

  /**
  * check a number optional -,+,. values
  * @param   string        
  * @return  boolean
  */
  function is_numeric($val)
  {
  return (bool)preg_match('/^[\-+]?[0-9]*\.?[0-9]+$/', $val);
 
  }

Validate for Phone Number

Use: validate given input is phone number

PHP function

  /**
  * Matches a phone number that length optional numbers 7,10,11
  * @param   string   
  * @return  boolean
  */
  function is_phone($number, $lengths = null)
  {
  if (!is_array($lengths)) {
  $lengths = array(7, 10, 11);
  }
  $number = preg_replace('/\D+/', '', $number);
  return in_array(strlen($number), $lengths);
 
  }

Validate Pincode

Use: validate given input is phone number

Regular Expression

We used more than one regular expression depending on countries

PHP function

  /**
  * Checks that given value matches following country pin codes.     
  * at = austria
  * au = australia
  * ca = canada
  * de = german
  * ee = estonia
  * nl = netherlands
  * it = italy
  * pt = portugal
  * se = sweden
  * uk = united kingdom
  * us = united states
  * @param String   
  * @param String
  * @return  boolean
  */
  function is_pincode($val, $country = 'us')
  {
  $patterns = array('at' => '^[0-9]{4,4}$', 'au' => '^[2-9][0-9]{2,3}$', 'ca' =>
  '^[a-zA-Z].[0-9].[a-zA-Z].\s[0-9].[a-zA-Z].[0-9].', 'de' => '^[0-9]{5,5}$', 'ee' =>
  '^[0-9]{5,5}$', 'nl' => '^[0-9]{4,4}\s[a-zA-Z]{2,2}$', 'it' => '^[0-9]{5,5}$',
  'pt' => '^[0-9]{4,4}-[0-9]{3,3}$', 'se' => '^[0-9]{3,3}\s[0-9]{2,2}$', 'uk' =>
  '^([A-Z]{1,2}[0-9]{1}[0-9A-Z]{0,1}) ?([0-9]{1}[A-Z]{1,2})$', 'us' =>
  '^[0-9]{5,5}[\-]{0,1}[0-9]{4,4}$');
  if (!array_key_exists($country, $patterns))
  return false;
  return (bool)preg_match("/" . $patterns[$country] . "/", $val);
 
 
  }

Validation for string lenght is with in range of given lengths

Use : This is the most common validation again user input values.

Regular Expression:

Here we used PHP handy functions.

PHP function

  /**
     * check given string length is between given range 
     * @param   string   
     * @return  boolean
     */
    function is_rangelength($val, $min = '', $max = '')
    {
        return (strlen($val) >= $min and strlen($val) <= $max);
    }

Validation for given integer value between given two values

Use : This is the most common validation again user input values.

Regular Expression:

Here we used PHP handy functions.

PHP function

   /**
     * check given number between given values
     * @param   string   
     * @return  boolean
     */
    function is_rangevalue($number,$min,$max)
    {
        return ($number > $min and $number < $max);
 
    }

Validation input value againest given regex

Use: in some cases we have use custom regular expression.

Regular Expression:

Here we used PHP handy functions.

PHP function

   /**
     * check given number between given values
     * @param   string   
     * @return  boolean
     */
    function is_rangevalue($number,$min,$max)
    {
        return ($number > $min and $number < $max);
 
    }

Validation for rgb colour value

use: we validate the user input is RGB color

rgb color Regular Expression:

/^(rgb\(\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*,\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*,\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*\))|(rgb\(\s*(\d?\d%|100%)+\s*,\s*(\d?\d%|100%)+\s*,\s*(\d?\d%|100%)+\s*\))$/

PHP function

   /**
     * Check is rgb color value
     * @param   string   
     * @return  boolean
     */
    function is_rgb($val)
    {
        return (bool)preg_match("/^(rgb\(\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*,\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*,\s*\b([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\b\s*\))|(rgb\(\s*(\d?\d%|100%)+\s*,\s*(\d?\d%|100%)+\s*,\s*(\d?\d%|100%)+\s*\))$/",
            $val);
    }

Validate time 12 hours format

use: Validate for 12 hours format time

12 hours format Regular Expression:

/^([1-9]|1[0-2]|0[1-9]){1}(:[0-5][0-9][aApP][mM]){1}$/

PHP function

   /**
     * Time in 12 hours format with optional seconds
     * 08:00AM | 10:00am | 7:00pm
     * @param   string         
     * @return  boolean
     */
    function is_time12($val)
    {
        return (bool)preg_match("/^([1-9]|1[0-2]|0[1-9]){1}(:[0-5][0-9][aApP][mM]){1}$/",
            $val);
    }

Validation for 24 hours format time

use: Validate for 24 hours format time

24 hours time format Regular Expression:

/^(([0-1]?[0-9])|([2][0-3])):([0-5]?[0-9])(:([0-5]?[0-9]))?$/

PHP function

  /**
     * Time in 24 hours format with optional seconds
     * 12:15 | 10:26:59 | 22:01:15 
     * @param   string         
     * @return  boolean
     */
 
    function is_time24($val)
    {
        return (bool)preg_match("/^(([0-1]?[0-9])|([2][0-3])):([0-5]?[0-9])(:([0-5]?[0-9]))?$/",
            $val);
    }

Validation for time zone format

use: Validate time zone format GMT

GMT time zone Regular Expression:

/^[-+]((0[0-9]|1[0-3]):([03]0|45)|14:00)$/

PHP function

  /**
     * Checks given value matches a time zone  
     * +00:00 | -05:00 
     * @param   string         
     * @return  boolean
     */
    function is_timezone($val)
    {
        return (bool)preg_match("/^[-+]((0[0-9]|1[0-3]):([03]0|45)|14:00)$/", $val);
    }

Validation for token

use: A token that don’t have white spaces.

Regular Expression:

/\s/

PHP function

 /**
     * A token that don't have any white space
     * @param   string   
     * @return  boolean
     */
    function is_token($val)
    {
        return (bool)!preg_match('/\s/', $val);
 
    }

Validate unique array elements

Use: in some times we ask user multiple choices ,so these elements are unique are not!!

PHP function

 /**
     * check if array has unique elements,it must have  minimum one element
     * @param   string   
     * @return  boolean
     */
    function is_unique($arr)
    {
        $arr = (array )$arr;
        $count1 = count($arr);
        $count2 = count(array_unique($arr));
        return (count1 != 0 and (count1 == $count2));
    }

Validation for input value is Upper case

Use: in experience i didn’t got any chance to validate this ,but it is may use full for others.

Regular Expression

/^[A-Z]+$/

PHP function

   /**
     * Given string is upper cased?
     * @param   string   
     * @return  boolean
     */
    function is_upper($val)
    {
        return (bool)preg_match("/^[A-Z]+$/", $val);
 
    }

Validation for URL

Use: validate given input is URL format

Regular Expression

PHP function

  /**
     * Valid URL or web address
     * @param   string      
     * @return  boolean
     */
    function is_url($val)
    {
        return (bool)preg_match("^((((https?|ftps?|gopher|telnet|nntp):\/\/)|(mailto:|news:))(%[0-9A-Fa-f]{2}|[-()_.!~*';\/?:@&=+$,A-Za-z0-9])+)([).!';\/?:,][[:blank:]])?$",
            $val);
 
    }

Validate URL exists

Use: some times given we need If URL works or not

PHP function

  /**
     * Check given url really exists?
     * @param   string   
     * @return  boolean
     */
    function is_urlexists($link)
    {
 
        return (bool)@fsockopen($link, 80, $errno, $errstr, 30);
 
    }

Validation for US Social security number

Use : validate the user input is valid US social security number format

US social security number Regular Expression:

/^\d{3}-\d{2}-\d{4}$/

PHP function

   /**
     * Checks given value matches us citizen social security number
     * @param   string         
     * @return  boolean
     */
    function is_usssn($val)
    {
        return (bool)preg_match("/^\d{3}-\d{2}-\d{4}$/", $val);
    }

Validation for utf8

Use: given file input string is UTF8 format

Regular Expression

PHP function

   /**
     * check given sting is UTF8 
     * @param   string  
     * @return  boolean
     */
    function is_utf8($val)
    {
        return preg_match('%(?:
        [\xC2-\xDF][\x80-\xBF]        
        |\xE0[\xA0-\xBF][\x80-\xBF]               
        |[\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}     
        |\xED[\x80-\x9F][\x80-\xBF]               
        |\xF0[\x90-\xBF][\x80-\xBF]{2}   
        |[\xF1-\xF3][\x80-\xBF]{3}                  
        |\xF4[\x80-\x8F][\x80-\xBF]{2}    
        )+%xs', $val);
 
    }

Use: i have noticed my tutorials are directly copied on other blogs without informing, i spent some man hours doing this , if you want refer please send me back link.

Download the code

60 validation functions with php

mahesh chari — Wed, 02 Feb 2011 14:48:01 +0000

Hello my readers, after one month of hard work , i created a validation class and made a complete tutorial with 60 php validation methods in PHP. here each functions works independently. These methods are used in every kind of web applications. even i written the functions in PHP, you can use them in Javascript also by taking regular expression directly. If any method i missing ,fixing or you get idea for implementing and adding here please contact me.we can use this php class in form validation.

Download the code

PHP validation functions

validation for alpha characters

Use: It validates only Alphabets i.e small and capital letters. Input parameter must be trimmed ,it won’t allow spaces also.

Regular Expression

/^([a-zA-Z])+$/i

Regular Expression has case insensitive modifier.

PHP function

   /**
     * Matches only alpha letters
     * @param   string   
     * @return  boolean
     */
    function is_alpha($val)
    {
        return (bool)preg_match("/^([a-zA-Z])+$/i", $val);
 
    }

Valid parameters

Mahesh
chari
PHP

Invalid parameters

Mahesh1
cha2ri
PHP5.0.2

validation for alphadash characters

Use: It validates only Alphabets and dashes (under score, dash) i.e small , capital letters,_,-. Input parameter must be trimmed ,it won’t allow spaces also.

Regular Expression

/^([a-zA-Z_-])+$/i

Regular Expression has case insensitive modifier.

PHP function

   /**
     * Matches alpha and dashes like -,_
     * @param   string  
     * @return  boolean
     */
    function is_alphadash($val)
    {
        return (bool)preg_match("/^([A-Za-z_-])+$/i", $val);
 
    }

Valid parameters

Mahesh
chari_
PHP_OOPS

Invalid parameters

Mahesh1
cha2ri
PHP5.0.2
$_POST

validate alpha numeric characters

Use: It validates only Alphabets and dashes (under score, dash) i.e small , capital letters,_,-. Input parameter must be trimmed ,it won’t allow spaces also.

alpha numeric characters regular Expression

/^([a-zA-Z0-9])+$/i

Regular Expression has case insensitive modifier.

PHP function

  /**
     * Matches alpha and numbers only
     * @param   string   
     * @return  boolean
     */
    function is_alphanumeric($val)
    {
        return (bool)preg_match("/^([a-zA-Z0-9])+$/i", $val);
 
    }

Valid parameters

Mahesh
chari
PHP OOPS

Invalid parameters

PHP5.0.2
$_POST

validation for ascii input from a file

Use: It is very important to work with multi language application , we must validate for utf-8, ascii characters.

ascii string format validate Regular Expression

  /[^\x00-\x7F]/i

PHP function

  /**
  * is given string is ascii format?
  * @param   string        
  * @return  boolean
  */
 
  function is_ascii($val)
  {
  return !preg_match('/[^\x00-\x7F]/i', $val);
  }

Valid parameter

We can’t display file specific characters here . just test with note pad text.

Invalid parameter

We can’t display file specific characters here . just test with note pad text.

base64 string Validation

Use: Generelly we encrypt the URL parameters with base64_encode and base64_decode from end users,while validating with sessions,passing secrate data. Then we must check that parameter string for valid base64 encoding.

base64 string Regular Expression

  /[^a-zA-Z0-9\/\+=]/

PHP function

  /**
  * Matches base64 enoding string
  * @param   string   
  * @return  boolean
  */
  function is_base64($val)
  {
  return (bool)!preg_match('/[^a-zA-Z0-9\/\+=]/', $val);
 
  }

Valid parameter

base64 encoded string

Invalid parameter

non base64 encoded string

Validation for boolean or Bool type

Use: Generelly we use so many type values for number (1,0), strings (‘yes’,'no’),(’1′,’0′),bool (true,false)

PHP function

Custom function that validates informal and formal type of boolean.

  /**
  * is given field is boolean value or not
  * @param   string   
  * @return  boolean
  */
  function is_boolean($val)
  {
  $booleans = array(1, 0, '1', '0', true, false, true, false);
  $literals = array('true', 'false', 'yes', 'no');
  foreach ($booleans as $bool) {
  if ($val === $bool)
  return true;
  }
 
  return in_array(strtolower($val), $literals);
  }

PHP core function

is_bool() can be used

Valid parameter

1,0,’yes’,'no’,true,false

Invalid parameter

any different paramenter from the above.

Validate credit card number

Use: E-Commerce applications uses,for user credit card validation.

credit card validation Regular Expression

/^((4\d{3})|(5[1-5]\d{2})|(6011)|(7\d{3}))-?\d{4}-?\d{4}-?\d{4}|3[4,7]\d{13}$/

credit card validation php function

  /**
  * Valid Credit Card
  * @param   string   
  * @return  boolean
  */
  function is_creditcard($val)
  {
  return (bool)preg_match("/^((4\d{3})|(5[1-5]\d{2})|(6011)|(7\d{3}))-?\d{4}-?\d{4}-?\d{4}|3[4,7]\d{13}$/",
  $val);
 
  }

Validation for date any format

Use: While validating time event dependent applications like organising,appointment..etc application we use date validation.

PHP function

  /**
  * Check if given string matches any format date
  * @param   string   
  * @return  boolean
  */
  function is_date($val)
  {
  return (strtotime($val) !== false);
 
  }

Validation for dateDe [d.m.y]

Use: While validating time event dependent applications like organising,appointment..etc application we use date validation.

date de validation Regular Expression

/^\d\d?\.\d\d?\.\d\d\d?\d?$/

PHP function

  /**
  * Checks given value matches date de
  * @param   string         
  * @return  boolean
  */
 
  function is_dateDE($date)
  {
  return (bool)preg_match("/^\d\d?\.\d\d?\.\d\d\d?\d?$/", $date);
  }

Validation for dateISO

Use: While validating time event dependent applications like organising,appointment..etc application we use date validation.

iso date Regular Expression

/^\d{4}[\/-]\d{1,2}[\/-]\d{1,2}$/

PHP validate date iso function

  /**
  * Checks given value matches us citizen social security number
  * @param   string         
  * @return  boolean
  */
  function is_dateISO($date)
  {
  return (bool)preg_match("/^\d{4}[\/-]\d{1,2}[\/-]\d{1,2}$/", $date);
  }

Validation for decimal

Use: Validation while processing ecommerce form for money values.

decimal validation Regular Expression

/^\d+(\.\d{1,6})?$/

PHP function

  /**
  * check decimal with . is optional and after decimal places up to 6th precision
  * @param   string   
  * @return  boolean
  */
  function is_decimal($val)
  {
  return (bool)preg_match("/^\d+(\.\d{1,6})?$/'", $val);
 
  }

Validation for email address

Use: validation on user registration ,contact forms.

email address validation Regular Expression

/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*@([a-z0-9\-]+\.)+[a-z]{2,6}$/ix

PHP email address validation function

  /**
  * valid email     
  * @param   string   
  * @return  boolean
  */
  function is_email($val)
  {
  return (bool)(preg_match("/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*@([a-z0-9\-]+\.)+[a-z]{2,6}$/ix",
  $val));
 
  }

validate email domain exists

Use: validation on user registration ,contact forms. Before testing this function check it is valid email.

email Regular Expression

/^[^@]++@/

PHP function

  /**
  * Checks that a field is exactly the right length.
  * @param   string   value
  * @link  http://php.net/checkdnsrr  not added to Windows until PHP 5.3.0
  * @return  boolean
  */
  function is_emaildomain($email)
  {
  return (bool)checkdnsrr(preg_replace('/^[^@]++@/', '', $email), 'MX');
 
  }

Validation for empty input for all type

Use: validate the input parameter that is string ,boolean,array ,object, null .etc types also for empty

PHP validate function

  /**
  * check if field empty string ,orject,array
  * @param   string   
  * @return  boolean
  */
  function is_empty($val)
  {
  return in_array($val, array(null, false, '', array(),(object)array()), true);
 
  }

Validation for enum

Use: we need to check a value for fixed number of specified values only, takes a input value and compares the given array, it is alias of in_array PHP function

PHP function

  /**
  * check given string againest given array values
  * @param   string   
  * @return  boolean
  */
  function is_enum($val, $arr)
  {
  return in_array($val, $arr);
 
  }

Validation for variable exists

Use: check if a array key element exists.

PHP function

  /**
  * check given array key element exists?
  * @param   string   
  * @return  boolean
  */
 
  function is_exists($val, $arr)
  {
  return isset($arr[$val]);
 
  }

Validate hexa decimal color

Use: validate the given value for hexa decimal color format

hexa decimal color Regular Expression

/^#?+[0-9a-f]{3}(?:[0-9a-f]{3})?$/i

PHP function

  /**
  * Valid hexadecimal color ,that may have #,
  * @param   string   
  * @return  boolean
  */
  function is_hexcolor($color)
  {
  return (bool)preg_match('/^#?+[0-9a-f]{3}(?:[0-9a-f]{3})?$/i', $color);
 
  }

Validate html tags

Use: It is best practice to validate our forms textarea elements data againest HTML content ,before we displaying HTML with Mysql data. If we don’t validate this will override our Web page template layout.

HTML tag Regular Expression

/<(.*)>.*<$1>/

PHP HTML tag validation function

  /**
  * given sting has html tags?
  * @param   string   
  * @return  boolean
  */
  function is_htmlsafe($val)
  {
  return (bool)(!preg_match("/<(.*)>.*
  <$1>
  /", $val));
 
  }

Validation for integer

Use: validate integer

validate input for integer php function

  /**
  *Matches exactly number
  * @param   string   
  * @return  boolean
  */
  function is_integer($val)
  {
  return is_int($val);
 
  }

Validate ip address

Use: It is best practice to validate user remote address with PHP , in some times user may comes as anonymus i.e Proxy enabled . it is best used in IP bound applications like polling, affiliate marketing applications..

ip address validation Regular Expression

/<(.*)>.*<$1>/

ip address validate php function

  /**
  * Valid IP address
  * @param   string   
  * @return  boolean
  */
  function is_ipaddress($val)
  {
  return (bool)preg_match("/^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/",
  $val);
 
  }

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regular expressions reference

mahesh chari — Fri, 10 Jul 2009 23:11:20 +0000

Regular Expressions Reference or Cheat Sheet

The regular expression, as a pattern, can match all kinds of text strings helping our web application validate, compare, sanitize data, compute, decide , format , data extraction 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.Below table shows a quick referece to basic syntax , definations and examlple.

Character	Definition	Example
^	The pattern has to appear at the beginning of a string.	^cat matches any string that begins with cat
$	The pattern has to appear at the end of a string.	cat$ matches any string that ends with cat
.	Matches any character.	cat. matches catT and cat2 but not catty
[]	Bracket expression. Matches one of any characters enclosed.	gr[ae]y matches gray or grey
[^]	Negates a bracket expression. Matches one of any characters EXCEPT those enclosed.	1[^02] matches 13 but not 10 or 12
[-]	Range. Matches any characters within the range.	[1-9] matches any single digit EXCEPT 0
?	Preceeding item must match one or zero times.	colou?r matches color or colour but not colouur
+	Preceeding item must match one or more times.	be+ matches be or bee but not b
*	Preceeding item must match zero or more times.	be* matches b or be or beeeeeeeeee
()	Parentheses. Creates a substring or item that metacharacters can be applied to	a(bee)?t matches at or abeet but not abet
{n}	Bound. Specifies exact number of times for the preceeding item to match.	[0-9]{3} matches any three digits
{n,}	Bound. Specifies minimum number of times for the preceeding item to match.	[0-9]{3,} matches any three or more digits
{n,m}	Bound. Specifies minimum and maximum number of times for the preceeding item to match.	[0-9]{3,5} matches any three, four, or five digits
\|	Alternation. One of the alternatives has to match. ‘or’ operater	July (first\|1st\|1) will match July 1st but not July 2
POSIX Character Classes
Character	Definition	Example
[:alnum:]	alphanumeric character	[[:alnum:]]{3} matches any three letters or numbers, like 7Ds
[:alpha:]	alphabetic character, any case	[[:alpha:]]{5} matches five alphabetic characters, any case, like aBcDe
[:blank:]	space and tab	[[:blank:]]{3,5} matches any three, four, or five spaces and tabs
[:digit:]	digits	[[:digit:]]{3,5} matches any three, four, or five digits, like 3, 05, 489
[:lower:]	lowercase alphabetics	[[:lower:]] matches a but not A
[:punct:]	punctuation characters	[[:punct:]] matches ! or . or , but not a or 3
[:space:]	all whitespace characters, including newline and carriage return	[[:space:]] matches any space, tab, newline, or carriage return
[:upper:]	uppercase alphabetics	[[:upper:]] matches A but not a
Perl-Style Metacharacters
Character	Definition	Example
//	Default delimiters for pattern	/colou?r/ matches color or colour
i	Append to pattern to specify a case insensitive match	/colou?r/i matches COLOR or Colour
\b	A word boundary, the spot between word (\w) and non-word (\W) characters	/\bfred\b/i matches Fred but not Alfred or Frederick
\B	A non-word boundary	/fred\B/i matches Frederick but not Fred
\d	A single digit character,this is equivalent to the class [0-9].	/a\db/i matches a2b but not acb
\D	A single non-digit character,this is equivalent to the class [^0-9].	/a\Db/i matches aCb but not a2b
\n	The newline character. (ASCII 10)	/\n/ matches a newline
\r	The carriage return character. (ASCII 13)	/\r/ matches a carriage return
\s	A single whitespace character,this is equivalent to the class [^ \t\n\r\f\v].	/a\sb/ matches a b but not ab
\S	A single non-whitespace character,this is equivalent to the class [^ \t\n\r\f\v].	/a\Sb/ matches a2b but not a b
\t	The tab character. (ASCII 9)	/\t/ matches a tab.
\w	A single word character – alphanumeric and underscore,this is equivalent to the class [a-zA-Z0-9_].	/\w/ matches 1 or _ but not ?,
\W	A single non-word character,this is equivalent to the class [^a-zA-Z0-9_].	/a\Wb/i matches a!b but not a2b

Php Development » regular expressions

60 validation functions with php 2 part

PHP validation functions

Validation for Javascript injection (jssafe)

Validation for String length

Validation for lower case String

Validate macaddress

Validation for strict Object matches

Validation for String lenght maximum

Validation for number maximum value

Validate md5 String

Validation for String minimum length

Validation for number minimum value

Validation for multy line characters.

Validation for numeric

Validate for Phone Number

Validate Pincode

Validation for string lenght is with in range of given lengths

Validation for given integer value between given two values

Validation input value againest given regex

Validation for rgb colour value

Validate time 12 hours format

Validation for 24 hours format time

Validation for time zone format

Validation for token

Validate unique array elements

Validation for input value is Upper case

Validation for URL

Validate URL exists

Validation for US Social security number

Validation for utf8

60 validation functions with php

PHP validation functions

validation for alpha characters

validation for alphadash characters

validate alpha numeric characters

validation for ascii input from a file

base64 string Validation

Validation for boolean or Bool type

Validate credit card number

Validation for date any format

Validation for dateDe [d.m.y]

Validation for dateISO

Validation for decimal

Validation for email address

validate email domain exists

Validation for empty input for all type

Validation for enum

Validation for variable exists

Validate hexa decimal color

Validate html tags

Validation for integer

Validate ip address

regular expressions reference

Regular Expressions Reference or Cheat Sheet

POSIX Character Classes

Perl-Style Metacharacters