<?

// Start the main function
StartValidate();

function StartValidate() {

    // Assign some var's for the requests
    $required = $_GET["required"];
    $type = $_GET["type"];
    $value = $_GET["value"];

    // This is the function to check if a field is even required or not
    // So it's useful if you only want to check if it isn't empty
    validateRequired($required, $value, $type);

    switch ($type) {
        case 'number':
            validateNumber($value);
            break;
        case 'alphanum':
            validateAlphanum($value);
            break;
        case 'alpha':
            validateAlpha($value);
            break;
        case 'date':
            validateDate($value);
            break;
        case 'email':
            validateEmail($value);
            break;
        case 'url':
            validateUrl($value);
            break;
    }
}

// The function to check if a field is required or not
function validateRequired($required, $value, $type) {
    if($required == "required") {

        // Check if we got an empty value
        if($value == "") {
            echo "false";
            exit();
        }
    } else {
        if($value == "") {
            echo "none";
            exit();
        }
    }
}

// I use regular expressions in order to check a field's input, you can
// get most of them at the Regex Library at http://www.regexlib.com
// There you can check your own regular expressions, too

// Validation of an Email Address
function validateEmail($value) {
    if(ereg("^([0-9a-zA-Z]+[-._+&])*[0-9a-zA-Z]+@([-0-9a-zA-Z]+[.])+[a-zA-Z]{2,6}$", $value, $regs)) {
        echo "true";
    } else {
        echo "false";
    }
}

// Validation of a date
function validateDate($value) {
    if(ereg("^(([1-9])|(0[1-9])|(1[0-2]))\/(([0-9])|([0-2][0-9])|(3[0-1]))\/(([0-9][0-9])|([1-2][0,9][0-9][0-9]))$", $value, $regs)) {
        echo "true";
    } else {
        echo "false";
    }
}

// Validation of an URL
function validateUrl($value) {
    if(ereg("^(http|https|ftp)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(:[a-zA-Z0-9]*)?/?([a-zA-Z0-9\-\._\?\,\'/\\\+&amp;%\$#\=~])*[^\.\,\)\(\s]$", $value, $regs)) {
        echo "true";
    } else {
        echo "false";
    }
}

// Validation of characters
function validateAlpha($value) {
    if(ereg("^[a-zA-Z]+$", $value, $regs)) {
        echo "true";
    } else {
        echo "false";
    }
}

// Validation of characters and numbers
function validateAlphanum($value) {
    if(ereg("^[a-zA-Z0-9]+$", $value, $regs)) {
        echo "true";
    } else {
        echo "false";
    }
}

// Validation of numbers
function validateNumber($value) {
    if(ereg("^[0-9]+$", $value, $regs)) {
        echo "true";
    } else {
        echo "false";
    }
}

?>