array_search() is case sensitive so that it is not matching. you can use str_ireplace() fo case insensitive replacement. rather than searching through the array you can directly replace the cid using str_ireplace(). if you need to determin the count of replacement occurance you can use the 4th param of that function. http://php.net/str_ireplace. that would be more efficcient.
str_replace('cid:', '', $srcArr,$occurance);if($occrance===0)echo 'No cid affix found<br />';