strtoupper some fields after submission

<?php
// http://www.gravityhelp.com/forums/topic/convert-form-field-text-to-uppercase
// change the 1 here to your form ID if it's not form 1
add_action('gform_pre_submission_1', 'capitalize_fields');
function capitalize_fields($form){
    // add all the field IDs you want to capitalize, to this array
    $fields_to_cap = array(
                    'input_1',
                    'input_19',
                    'input_1',
                    'input_19',
                    'input_20',
                    'input_21',
                    'input_3',
                    'input_22',
                    'input_4',
                    'input_5',
                    'input_18',
                    'input_24',
                    'input_10',
                    'input_11',
                    'input_13',
                    'input_14',
                    'input_15',
                    'input_28');
    foreach ($fields_to_cap as $each) {
        // for each field, convert the submitted value to uppercase and assign back to the POST variable
        // the rgpost function strips slashes
        $_POST[$each] = strtoupper(rgpost($each));
    }
    // return the form, even though we did not modify it
    return $form;
}