How can consistency checks be implemented in PHP forms to ensure valid user input before sending messages?

Consistency checks in PHP forms can be implemented by validating user input using conditional statements and regular expressions. This ensures that the data entered by the user meets the required criteria before processing or sending messages. By checking for consistency in the input fields, it helps prevent errors and ensures that only valid data is submitted. 

// Example of implementing consistency checks in a PHP form
$name = $_POST['name'];
$email = $_POST['email'];

// Check if name contains only letters and spaces
if (!preg_match("/^[a-zA-Z ]*$/", $name)) {
    echo "Invalid name format. Please enter letters and spaces only.";
}

// Check if email is a valid email address
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo "Invalid email format. Please enter a valid email address.";
}

Keywords

validation form handling input sanitization error handling data validation

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