What are the potential pitfalls of using global variables in PHP form validation functions?

Using global variables in PHP form validation functions can lead to issues such as variable scope conflicts, making the code harder to maintain and debug. To avoid these pitfalls, it is recommended to pass variables as parameters to the validation function instead of relying on global variables. 

// Incorrect way using global variables
$errorMessage = '';

function validateForm() {
    global $errorMessage;
    // validation logic
}

// Correct way passing variables as parameters
function validateForm($errorMessage) {
    // validation logic
}

// Usage
$errorMessage = '';
validateForm($errorMessage);

Keywords

global variables PHP form validation security vulnerabilities data leakage

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