Form Validation of Multiple errors - php

Question

What would be the best way to code for the following
To check if its empty
That its alpha
Length
I am wanting a way that I am able to combine the following if statements
Current Code
if (isset($_POST['submitButton'])) {
$fullName = $_POST['fullname'];
if(fullName != ' ')
{
$errorfullName .= 'Please Enter Your Name';
}
}
}
if statements that need to be included:
if (!ctype_alpha(str_replace(array("'", "-"), "",$fullName))) {
$errorfullName .= '<span class="errorfullName">*First name should be alpha characters only.</span>';
}
if (strlen($fullName) < 3 OR strlen($fullName) > 40) {
$errorfullName .= '<span class="errorfullName">*First name should be within 3-40 characters long.</span>';
}

Answer 1

Your are missing $ sign before fullName.Use empty function to check weather the string is empty or not. Use the below code
if (isset($_POST['submitButton'])) {
$fullName = $_POST['fullname'];
if(empty($fullName))
{
$errorfullName .= 'Please Enter Your Name';
}
}

Answer 2

If you need to combine more statements, you can do it with ( if{} elseif{} else{/*NO ERROR*/}. But I think there is a smarter solution:
function valide_fulname($fullname) {
if (isset($fullName) && trim($fullName)!='')
return 'Please enter your name.';
if (!ctype_alpha(str_replace(["'", "-"], "", $fullName)))
return 'First name should be alpha characters only.';
if (strlen($fullName)<3 || strlen($fullName)>40)
return 'First name should be within 3-40 characters long.';
// no error
return false;
}
if (isset($_POST['submitButton'])) {
$error = valide_fullname($_POST['fullname']);
if (!$error)
echo "It's OK!";
else
echo '<span class="errorfullName">' . $error . '</span>';
}