How can special characters or encoding issues in variables affect the functionality of the header function in PHP?

Special characters or encoding issues in variables can affect the functionality of the header function in PHP by causing unexpected behavior or errors. To solve this issue, it is important to properly encode the variables before using them in the header function to ensure that special characters are handled correctly.

// Encode the variable using urlencode before using it in the header function
$variable = urlencode($variable);
header("Location: http://example.com/page.php?var=$variable");