PHP form validation number fields - php

Question

I need this field to only allow numbers to be input to the field and there must be 11 digits that have been input into the "Mobile Number" field, this is the form I have created
<form name="myForm" id="userDetails" action="formProcess.php" onSubmit="return validateForm()" method="post">
<fieldset class="custInf">
<h3> User Details </h3>
<label class="inputArea" for="fName">Forename :</label>
<input type="text" name="forename" id="fname" placeholder="Enter First Name" maxlength="20" size="15"></input>
<label class="inputArea" for="sName">Surname :</label>
<input type="text" name="surname" id="surname" placeholder="Enter Last Name" maxlength="20" size="15"></input>
<label class="inputArea" for="email">Email :</label>
<input type="email" name="email" id="email" placeholder="Enter Email Address" maxlength="40" size="15" /></input>
<label class="inputArea" for="hmph">Landline number :</label>
<input type="tel" name="landLineTelNo" id="hmphone" placeholder="Enter Landline no." maxlength="11" size="15"></input>
<label class="inputArea" for=" mobileTelNo">Mobile number :</label>
<input type="tel" name=" mobileTelNo" id="mobile" placeholder="Enter Mobile no." maxlength="11" size="15"></input>
<label class="inputArea" for="address">Postal Address :</label>
<input type="text" name="postalAddress" id="address" placeholder="Enter House no." maxlength="25" size="15"></input>
</fieldset>
<fieldset class="contactType">
<h3>
How would you like to be contacted?
</h3>
<label class="radioBt" for="sms">SMS</label>
<input id="smsBut" type="radio" name="sendMethod" value="SMS"></input>
<label class="radioBt" for="email">Email</label>
<input type="radio" name="sendMethod" value="Email"></input>
<label class="radioBt" for="post">Post</label>
<input type="radio" name="sendMethod" value="Post"></input>
</fieldset>
<fieldset class="termsCon">
<input type="checkbox" name="check" value="check" id="check" />I have read and agree to the Terms and Conditions and Privacy Policy</input>
</fieldset>
<input class="submitBut" type="submit" name="submitBut" value="Submit" </input>
Here is the PHP I have created so far to validate the user input `//Ensures user enters information required
$fname = $_REQUEST['forename'];
if (empty($fname)) {
die("<p>Enter a first name</p>\n");
}
$surname = $_REQUEST['surname'];
if (empty($surname)) {
die("<p>You must enter a surname</p>\n");
}
$email = $_REQUEST['email'];
if (empty($email)) {
die("<p>You need to enter an email</p>\n");
}
$hmphone = isset($_REQUEST['hmph']) ? $_REQUEST['hmph'] : null ;
$mobile = $_REQUEST['mobileTelNo'];
if (empty($mobile)) {
die("<p>Enter a Mobile Number</p>\n");
}
$address = $_REQUEST['postalAddress'];
if (empty($address)) {
die("<p>Enter your postal address</p>\n");
}
$sendMethod = $_REQUEST['sendMethod'];
if (empty($sendMethod)) {
die("<p>Please choose a contact option</p>\n");
}
$check = $_REQUEST['check'];
if (empty($check)) {
die("<p>Please select the Terms and Conditions to continue</p>\n");
}`

Answer 1

You can pattern match inside the form by adding the following code inside the relevant input field thanks to the html5 pattern tag. More details on the pattern tag here: http://www.w3schools.com/tags/att_input_pattern.asp
pattern="[0-9]{11}"
It's quite similar on the server side php checking thankfully!
$isValid = preg_match("/[0-9]{11}/", $formvalue);
$isValid will return true (1) if it matches or false (0) if it doesn't match.
preg_match is a very useful function in general for custom validation. There's more details on it available here: http://php.net/manual/en/function.preg-match.php

Answer 2

If you're sure your rule is correct you can do this:
if (empty($mobile) || preg_match('/^[0-9]{11}$/', $mobile) != 1 ) {
die("<p>Enter a Mobile Number</p>\n");
}
from the docs:
preg_match() returns 1 if the pattern matches given subject, 0 if it does not, or FALSE if an error occurred.
The regular expression explained:
^ assert position at start of the string
[0-9] match a single character present in the list below
Quantifier: {11} Exactly 11 times
0-9 a single character in the range between 0 and 9
$ assert position at end of the string

Answer 3

you can validate with this:
if(empty($number)) {
echo '<p> Please enter a value</p>';
} else if(!is_numeric($number)) {
echo '<p> Data entered was not numeric</p>';
} else if(strlen($number) != 11) {
echo '<p> The number entered was not 6 digits long</p>';
}