PHP Basic (iv) Form validation

This article is from http://www.w3school.com.cn/php/php_form_url_email.asp

PHP Form Verification-Verify e-mail and URLs

This section shows you how to verify your name, email, and URL.

PHP-Validating names

The following code shows a simple way to check whether the Name field contains letters and spaces. If the name field is not valid, an error message is stored:

$name = Test_input ($_post["name"]); if (!preg_match ("/^[a-za-z]*$/", $name)) {  = "Only letters and spaces are allowed! "; }

Note: the Preg_match () function retrieves the pattern of a string and returns True if the pattern exists, otherwise false.

PHP-Verify e-mail

The following code shows a simple way to check whether the e-mail address syntax is valid. If it is not valid, an error message is stored:

$email = test_input ($_post["email"]); if (!preg_match ("/([\w\-]+\@[\w\-]+\.[ \w\-]+)/", $email)) {  =" Invalid email format! "; }

PHP-Validating URLs

The following code shows a method that checks whether the URL address syntax is valid (this regular expression also allows a slash in the URL). If the URL address syntax is invalid, an error message is stored:

$website = test_input ($_post["website"]); if (!preg_match/\b (?:(?: https?| FTP): \/\/|www\.) [-a-z0-9+&@#\/%?=~_|!:,.;] *[-a-z0-9+&@#\/%=~_|] /I ", $website))  {=" Invalid URL ";}

PHP Validation Example

<?php//defines the variable and sets it to a null value $nameerr = $EMAILERR = $GENDERERR = $WEBSITEERR = ""; $name = $email = $gender = $comment = $website =   "", if ($_server["request_method"] = = "POST") {if (Empty ($_post["name")) {$NAMEERR = "name is required";     } else {$name = Test_input ($_post["name"]);      Check if the name contains letters and whitespace characters if (!preg_match ("/^[a-za-z]*$/", $name)) {$NAMEERR = "allow only letters and spaces";   }} if (Empty ($_post["email")) {$EMAILERR = "e-mail is required";     } else {$email = Test_input ($_post["email"]); Check that the e-mail address syntax is valid if (!preg_match ("/"/([\w\-]+\@[\w\-]+\.[      \w\-]+)/", $email)) {$EMAILERR =" Invalid email format ";   }} if (Empty ($_post["website")) {$website = "";     } else {$website = Test_input ($_post["website"]); Check that the URL address syntax is valid (the regular expression also allows a slash in the URL) if (!preg_match ("/\b" (?:(?: https?| FTP): \/\/|www\.) [-a-z0-9+&@#\/%?=~_|!:,.;] *[-a-z0-9+&@#\/%=~_|]      /i ", $website)) {$WEBSITEERR =" Invalid URL "; }} if (Empty ($_post["comment")) {$comment = "";   } else {$comment = Test_input ($_post["comment"]);   } if (Empty ($_post["gender")) {$GENDERERR = "gender is required";   } else {$gender = Test_input ($_post["gender"]);   }}function Test_input ($data) {$data = Trim ($data);   $data = Stripslashes ($data);   $data = Htmlspecialchars ($data); return $data;}? ><?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>"> Name: <input type=" text "name=" name "> <span class=" Error ">*<?php echo $nameErr;?></span> <br><br> Email: <input type= "text" name= "email" > <span class= "Error" >*<?php echo $emailErr;?></span> <br><br> URL: <input type= "text" name= "website" > <span class= "Error" ><?php echo $websiteErr;?></span> <br><br> Comments: <textarea name= "comment" rows= "5" cols= "+" ></textarea> <br> <br> Gender: <input type= "Radio" name= "Gender" value= "female" > Female <input type= "Radio" name= "Gender" value= "Male" > Male <span class= "error" >*<?php echo $genderErr;?></span> <br><br> <input type= "Submit" name= "Submit" value= "Submission" > </form><?phpecho "</body>
PHP Basic (iv) Form validation