Why does cmd DIR search include files that start with the 3 searched letters but then differ?

Question

If in a directory I have two files, test.pro and test.properties, and I run dir /s *.pro to find all files with the .pro extension, it lists both files. However, when I run dir /s *.pr, it lists neither. Why does searching for a three-letter file extension list files with extensions that start with the three letters? How can I search for ONLY .pro files using dir?

Answer 1

The command DIR lets the file system search for file system entries (file names, directory names, reparse points (links)) matching the wildcard pattern *.pro in long name or in short 8.3 name on short name management also enabled for the file system of current drive.

The short file name of test.pro is TEST.PRO.
The short file name of test.properties is TEST~1.PRO.

Therefore the wildcard pattern *.pro matches test.pro and TEST~1.PRO displayed with long file name test.properties.

The wildcard pattern *.pr does not match with the two file names because of the file extension is pro respectively properties and not just pr. The wildcard pattern *.pr? would also find the file names test.pro and TEST~1.PRO displayed with long file name test.properties.

There can be used %SystemRoot%\System32\where.exe /R . *.pro to find recursively in current directory and all its subdirectories files with file extension .pro not matching file names with a longer file extension beginning with pro because of WHERE applies the wildcard pattern only on long file names.

DIR and also FOR use the Windows file I/O function which directly searches with the wildcard pattern *.pro for suitable file system entries. WHERE uses the Windows file I/O function to search for * to get a list of long names of all file system entries and then applies the wildcard pattern itself on each string returned by the file system. For that reason the usage of the wildcard pattern *.pro returns a positive result only on test.pro and not on test.properties on using WHERE.