Undefined array key "HTTP_USER_AGENT" - arrays

Question

Trying to solve an Undefined array key warning for "HTTP_USER_AGENT" for this line of code:
if ( ( strstr( $_SERVER['HTTP_USER_AGENT'], 'MSIE' ) == false ) && ( $use_object_frame == true ) ) {
Whole function:
`// Start widget output
$title = apply_filters( 'widget_title', empty( $instance\['title'\] ) ? \_\_( 'Shopping Cart', 'wp-e-commerce' ) : $instance\['title'\] );
echo $before_widget;
if ( $title )
echo $before_title . $title . $fancy_collapser . $after_title;
// Set display state
$display_state = '';
if ( ( ( isset( $_SESSION['slider_state'] ) && ( $_SESSION['slider_state'] == 0 ) ) || ( wpsc_cart_item_count() < 1 ) ) && ( get_option( 'show_sliding_cart' ) == 1 ) )
$display_state = 'style="display: none;"';
// Output start, if we are not allowed to save results ( WPSC_DONT_CACHE ) load the cart using ajax
$use_object_frame = false;
if ( WPSC_PAGE_CACHE_IN_USE ) {
echo '<div id="sliding_cart" class="shopping-cart-wrapper">';
if ( ( strstr( $_SERVER['HTTP_USER_AGENT'], 'MSIE' ) == false ) && ( $use_object_frame == true ) ) {
?>
<object codetype="text/html" type="text/html" data="index.php?wpsc_action=cart_html_page" border="0">
<p><?php _e( 'Loading...', 'wp-e-commerce' ); ?></p>
</object>
<?php
} else {
?>
<div class="wpsc_cart_loading"><p><?php _e( 'Loading...', 'wp-e-commerce' ); ?></p></div>
<?php
}
echo '</div>';
} else {
echo '<div id="sliding_cart" class="shopping-cart-wrapper" ' . $display_state . '>';
include( wpsc_get_template_file_path( 'wpsc-cart_widget.php' ) );
echo '</div>';
}
// End widget output
echo $after_widget;
}`
Looked online for similar issues.

Answer 1

To prevent the "Undefined array key" warning.you can add a check for the existence of the "HTTP_USER_AGENT" key in the $_SERVER array before accessing it:
if ( array_key_exists('HTTP_USER_AGENT', $_SERVER) && ( strstr( $_SERVER['HTTP_USER_AGENT'], 'MSIE' ) == false ) && ( $use_object_frame == true ) ) {
//Your code goes here.
}