Better practice to throw custom PHP errors using procedural way - php

Question

I know this question may be asked previously but I want to show my code and I would like to know that whether am doing a simple thing or complicating the code? Moreover answers say use try and catch but am going with procedural method so I would like to know that am I going right?
What I do it, for example a contact form
<?php
if(isset($_POST['contact'])) {
$throw_error = array();
//First Block Is Validation
if($_POST['first_name'] == '' || $_POST['last_name'] == '') {
$throw_error['field_blank'] = 'Fields Cannot Be Blank';
} elseif(strlen($_POST['first_name']) < 3) {
$throw_error['char_len'] = 'First Name Cannot Be Less Than 3 Characters';
}
//Second Block Is Process If No Errors Are Found
if(empty($throw_error)) {
$first_name = $_POST['first_name'];
//Don't worry about the sanitizing part, am doing it
//Process the form ahead and then redirect using header()
}
} elseif(!empty($throw_error)) { //Third Block To Throw Error If Any Errors Found
if(isset($throw_error['field_blank'])) {
echo $throw_error['field_blank'];
} elseif(isset($throw_error['char_len'])) {
echo $throw_error['char_len'];
}
}
?>
<form>
<input type="text" name="first_name" />
<input type="text" name="last_name" />
<input type="submit" value="Submit" name="contact" />
</form>

Answer 1

I would also recommend using Try/Catch. You can still use it in procedural blocks.
If you are dead set against it, this code looks like it will do what you want it to do, but it's over-engineered. Since the user can either have a field_blank or char_len error, you only need a single string error variable.
$error = NULL;
if($_POST['first_name'] == '' || $_POST['last_name'] == '') {
$error = 'Fields Cannot Be Blank';
} elseif(strlen($_POST['first_name']) < 3) {
$error = 'First Name Cannot Be Less Than 3 Characters';
}
...
if(!empty($error)) {
echo $error;
}
If you need to catch and display multiple non-exclusive errors, you can use the array you cited in your sample code and just iterate over the values rather than making a giant if/elseif block.
} elseif(!empty($throw_error)) { //Third Block To Throw Error If Any Errors Found
foreach($throw_error as $key => $message) {
echo $message.'<br>';
}
}

Answer 2

A try/catch you be great here. It eliminates all necessary for a throw_error array, as well as cuts down dramatically on the code.
try{
$first_name = '';
if(isset($_POST['contact'])) {
if($_POST['first_name'] == '' || $_POST['last_name'] == '') {
throw new Exception('Fields Cannot Be Blank');
} elseif(strlen($_POST['first_name']) < 3) {
throw new Exception('First Name Cannot Be Less Than 3 Characters');
}
$first_name = $_POST['first_name'];
}
}catch(Exception $e){
echo $e->getMessage();
}
If you were looking to pass an array to this catch statement, the easist way that I have found, is to serialize the array, then unserialize once complete. This will allow you to print all errors at once:
try{
$first_name = '';
if(isset($_POST['contact'])) {
if($_POST['first_name'] == '' || $_POST['last_name'] == '') {
$throw_error[] = 'Fields Cannot Be Blank';
}
if(strlen($_POST['first_name']) < 3) {
$throw_error[] = 'First Name Cannot Be Less Than 3 Characters';
}
if(isset($throw_error)){
throw new Exception(serialize($throw_error));
}
$first_name = $_POST['first_name'];
}
}catch(Exception $e){
$errors = unserialize($e->getMessage());
foreach($errors as $error){
echo $error.'<br>';
}
}