complete form validation in php - php

Question

I have this php code associated with a database and I need here to make a complete email and name validation
based on this code how can I do that because my code has some issues here
1)name key doesn't have (//) or any symbols to be a correct name
2)email key is valid email because what we did here just make ensure that there is # symbol and if I type the email hhhh#hhh.com or even without( .com ) it will be valid also ?!!
if(array_key_exists("submit",$_POST)){
$link = mysqli_connect("localhost","root","123456789","users");
if(mysqli_connect_error()){
die("There is a problem in connecting to database");
}
if(!$_POST['name']){
$error .="<p>Your Full name is required</p><br>";
}
if(!$_POST['email']){
$error .="<p>Your email address is required</p><br>";
}
if(!$_POST['password']){
$error .="<p>Your password is required</p><br>";
}
if($error !=""){
$error = "<p>There were errors in your form</p><br>".$error;
}
}

Answer 1

You can use this function for the validation:
function filtervariable($string,$type,$method) {
//function for sanitizing variables using PHPs built-in filter methods
$validEmail = false;
if ($method == 'sanitize') {
$filtermethod = 'FILTER_SANITIZE_';
} elseif ($method == 'validate') {
$filtermethod = 'FILTER_VALIDATE_';
} else {
return;
}
switch ($type) {
case 'email':
case 'string':
case 'number_int':
case 'int':
case 'special_chars':
case 'url':
$filtertype = $filtermethod.strtoupper($type);
break;
}
if ($filtertype == 'FILTER_VALIDATE_EMAIL' && !empty($string)) {
list($local,$domain) = explode('#',$string);
$localLength = strlen($local);
$domainLength = strlen($domain);
$checkLocal = explode('.',$domain);
if (($localLength > 0 && $localLength < 65) && ($domainLength > 3 && $domainLength < 256) && (checkdnsrr($domain,'MX') || checkdnsrr($domain,'A') || ($checkLocal[1] == 'loc' || $checkLocal[1] == 'dev' || $checkLocal[1] == 'srv'))) { // check for "loc, dev, srv" added to cater for specific problems with local setups
$validEmail = true;
} else {
$validEmail = false;
}
}
if (($filtertype == 'FILTER_VALIDATE_EMAIL' && $validEmail) || $filtertype != 'FILTER_VALIDATE_EMAIL') {
return filter_var($string, constant($filtertype));
} else {
return false;
}
}
And use it like this:
$email = filtervariable($registeremail,'email','validate');
It will return "true" on success and "false" on failure.