How to dectect if a file exist in specific Folder

Dear all I had a folder which contain some pdf report, the name of the Report will be : xxx.xxx.20020702.pdf. Here is what i want to do : 1. there will be a Form let user to submit the date of reports that he / she wants to view. 2. the php will get the xxx.xxx from a mysql database and add the date at the end of the string as the file name. 3. If the filename exist in that specific folder, then it will show a hyperlink for each exist report, otherwise nothing will shows up! I want to know how i can use php to detect if such file is exist in that specific Folder? -- Thx a lot! Jack nedcor4@nedcor.com.hk