alternate text with a special number

[ward4all]

I am using this code to add one alt text to all website images

if (stristr($navigator_user_agent, "msie")) {
return '<a href="' . $link . '" target="_blank"><img src="' . $link . '" alt="crafts" style="width: expression(this.width > 501 ? 500 : true);" /></a>';
}
else {
return '<img src="' . $link . '" title="ward2u fourm arts" alt="ward2u - 1" style="max-width: 500px;" /></a>';
} /* End Image RESIZE */

}

How can I add the same text with numbers from 1 to 20?
If the page has 20 pictures
Each image has alternate text with a special number
as in the following example:

alt="ward2u - 1"

alt="ward2u - 2"

alt="ward2u - 3"