Only show theme option if it option exists

Question

I have a slideshow in a custom theme I am developing and I am using the UpThemes Framework, what I want to know is, is there a way and image will only display if it has been defined?

For example, at the moment the max. number of images in the slideshow is 6, but if only 5 are uploaded the "alt" attribute displays for the 6th

For those unfamiliar with the framework, this is the PHP tag I am using

<?php echo $up_options->slideshow6; ?>

I have done this with custom fields in the past but I can't for the life of me figure out how I did it.

Answer 1

If you're wanting to output based on the option being defined, then use isset(). e.g. this:

<?php echo $up_options->slideshow6; ?>

...becomes this:

<?php 
if ( isset( $up_options->slideshow6 ) ) {
    echo $up_options->slideshow6;
}
?>

EDIT

How would I get the following to appear only if "slideshow6" was defined <a href="#"><img src="<?php echo $up_options->slideshow1; ?>" alt="#"/></a>

I would go with:

<?php 
if ( isset( $up_options->slideshow6 ) ) {
    echo '<a href="#"><img src="' . $up_options->slideshow1 . '" alt="#"/></a>';
}
?>