Question

How to validate a string in PHP

Answer 1

// The rules depend on your needs

function validateString($string, $minLength = 1, $maxLength = 255, $pattern = "/^[a-zA-Z0-9\s]+$/") {
    // Check length
    if (strlen($string) < $minLength || strlen($string) > $maxLength) {
        return false;
    }
    
    // Check pattern
    if (!preg_match($pattern, $string)) {
        return false;
    }
    
    return true;
}

$str = "PHP Programming";
if (validateString($str, 6, 55)) {
    echo "Valid string!";
} else {
    echo "Invalid string!";
}




/*
run:

Valid string!

*/

 

70+ SQL courses for beginners and professionals

Answer 2

// The rules depend on your needs

function validateString($string, $rules = []) {
    // Default rules
    $defaultRules = [
        'minLength' => 1,
        'maxLength' => 255,
        'pattern' => "/^[a-zA-Z0-9\s]+$/"
    ];
    
    // Merge default rules with custom rules
    $rules = array_merge($defaultRules, $rules);
    
    // Check length
    if (strlen($string) < $rules['minLength'] || strlen($string) > $rules['maxLength']) {
        return false;
    }
    
    // Check pattern
    if (!preg_match($rules['pattern'], $string)) {
        return false;
    }
    
    return true;
}

$str = "PHP Programming";
$customRules = [
    'minLength' => 6,
    'maxLength' => 55,
    'pattern' => "/^[a-zA-Z\s]+$/"
];

if (validateString($str, $customRules)) {
    echo "Valid string!";
} else {
    echo "Invalid string!";
}



/*
run:

Valid string!

*/

 

70+ SQL courses for beginners and professionals

Answer 3

// The rules depend on your needs

function validateString($string, $callbacks = []) {
    foreach ($callbacks as $callback) {
        if (!call_user_func($callback, $string)) {
            return false;
        }
    }
    return true;
}

// Custom validation functions
function checkLength($string) {
    return strlen($string) >= 6 && strlen($string) <= 55;
}

function checkPattern($string) {
    return preg_match("/^[a-zA-Z\s]+$/", $string);
}

$str = "PHP Programming";
$callbacks = ['checkLength', 'checkPattern'];

if (validateString($str, $callbacks)) {
    echo "Valid string!";
} else {
    echo "Invalid string!";
}



/*
run:

Valid string!

*/

 

70+ SQL courses for beginners and professionals