Code-Snippets-Functions/Execute a function on a child site/WooCommerce/auto-apply-a-predefined-coupon-code-for-any-imputted-5-character-coupon-code.txt

add_action( 'woocommerce_coupon_code', 'replace_5_char_coupon_code' );
function replace_5_char_coupon_code( $coupon_code ) {
    // If the coupon code has exactly 5 characters
    if ( strlen($coupon_code) === 5 ) {
        $coupon_code = 'PREDEFINED50'; // coupon code replacement
    }
    return $coupon_code;
}