Image blacklist – test a string against a blacklist in PHP

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/////////////////////////////
// Function

// compare string to a blacklist of image url fragments to avoid
function imageBlacklist($str){
	// words to filter
	$badwords = array( "//feeds.", "b.gif", "//api." );
	$result_of_filter = 0;
	foreach ($badwords as $value) {
		//echo($value);
	    $find_pos = strpos($str,$value);
	    if ($find_pos > 0) {
	    	$result_of_filter = 'blacklisted';
	    	break;
		}
	}
	unset($value); // break the reference with the last element
	return $result_of_filter;
}


/////////////////////////////
// usage 

// $test_this contains an example string — an image URL
$test_this = "http://example.com/images.b.gif";
// invoke the function to check our example string
$test_result = imageBlacklist($test_this);
// if the function returns blacklist we know a match was found
if ($test === 'blacklisted') {
	// use the fall back image url instead
	echo("<img src='http://example.com/backup-image.png' alt='' />");
} else {
	// the url is not on black list so use for our image
	echo("<img src='".$test_this."' alt='' />");
}

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