Working with files located on USB devices

[euklides]

When you write a program using files located on USB drives, you don't
'be sure that the letter of this drive is always the same.
So you can use this little program

Code: QB64: [Select]

1.  
2. 'LETTER_OF_USB_DEVICE  'program by Euklides
3. 'Working with files on USB devices
4.  
5. 'When you write a program using files located on USB drives, you don't be
6. 'sure that the letter of this drive is always the same.
7. 'You cannot write for instance:
8.  
9. '         OPEN "F:\MYFILE\info.txt" FOR INPUT AS #1
10. '         ...
11.  
12. 'If your drive has a new letter, for instance "E", you must go into your program
13. ' and change the letter
14. 'So what you can do is this:
15.  
16. '1) '  find the serial of your drive
17. '  Use below:
18.  
19. '         GOSUB SERIALSSHOW
20.  
21. '  and you will see all the serials of then actuel connected drives
22. '  For instance, the good drive has the serial "<9911-447E>
23.  
24. '2) Now write your program so:
25.  
26. '        fic$ = "<9911-447E>:\MYFILE\info.txt"
27. '        GOSUB DRIVELETTERFIND: IF _CLIPBOARD$ = "" THEN PRINT "USB unit is not connected for using " + fic$: END
28. '        fic$ = _CLIPBOARD$:OPEN fic$ FOR INPUT AS #1
29. '       ...
30.  
31.  
32. END
33.  
34.  
35. '=====================================================================
36. DECLARE DYNAMIC LIBRARY "kernel32"
37. FUNCTION GetVolumeInformationA& (lpRootPathName$, lpVolumeNameBuffer$, BYVAL nVolumeNameSize~&, _
38.     lpVolumeSerialNumber~&, lpMaximumComponentLength~&, lpFileSystemFlags~&, lpFileSystemNameBuffer$, BYVAL nFileSystemNameSize&)
39. END DECLARE
40. DECLARE LIBRARY: FUNCTION GetDriveType& (d$): END DECLARE
41. DIM SHARED DriveType AS STRING, SERIALFOUND AS STRING
42. '---
43. SERIALSSHOW:
44. FOR q = 1 TO 26: X = GetFileInfo(q): IF SERIALFOUND <> "<!!!-!!!>" THEN PRINT " "; CHR$(64 + q) + ":    "; SERIALFOUND
45. NEXT q
46. END
47. '---
48. DRIVELETTERFIND: 'in-->fic$ like' "<SER-IAL>ficname"  out--> like "D:\ficname"
49. _CLIPBOARD$ = "": K$ = UCASE$(LEFT$(fic$, 2))
50. IF RIGHT$(K$, 1) = ":" AND LEFT$(K$, 1) >= "A" AND LEFT$(K$, 1) <= "Z" AND DRIVEEXISTS(ASC(K$) - 64) = 1 THEN _CLIPBOARD$ = fic$: RETURN
51. J1 = INSTR(fic$, "<"): J2 = INSTR(J1, fic$, ">")
52. IF J1 = 0 OR J2 = 0 THEN PRINT fic$; " must be written like: <serial>\ficmame...": END
53. Serialsearch$ = MID$(fic$, J1, J2 - J1 + 1): q = 0
54. FOR q = 1 TO 26: X = GetFileInfo(q)
55.     IF SERIALFOUND = Serialsearch$ THEN
56.         fic$ = RIGHT$(fic$, LEN(fic$) - J2): IF LEFT$(fic$, 1) <> ":" THEN fic$ = ":" + fic$
57.         fic$ = CHR$(64 + q) + fic$: _CLIPBOARD$ = fic$
58.     END IF
59. NEXT q
60. RETURN
61. '---
62. FUNCTION GetFileInfo (D)
63.     SERIALFOUND = "<!!!-!!!>":
64.     IF DRIVEEXISTS(D) <> 1 THEN GetFileInfo = 0: EXIT FUNCTION
65.     Dname$ = CHR$(D + 64) + ":\": Sname$ = SPACE$(260)
66.     R = GetVolumeInformationA(Dname$ + CHR$(0), Vname$, 260, serial~&, empty1~&, empty2~&, Sname$, 260)
67.     IF R = 0 THEN EXIT FUNCTION
68.     Sname$ = LEFT$(HEX$(serial~&), 4) + "-" + RIGHT$(HEX$(serial~&), 4)
69.     SERIALFOUND = "<" + Sname$ + ">"
70.     GetFileInfo = -1
71. END FUNCTION
72. '---
73. FUNCTION DRIVEEXISTS (V)
74.     DRIVEEXISTS = 0: varX$ = CHR$(V + 64) + ":\" + CHR$(0): VarX = GetDriveType(varX$): IF VarX > 1 THEN DRIVEEXISTS = 1
75. END FUNCTION
76. '=====================================================================
77.  
78.  

[RhoSigma]

That's a nice method euklides.
As the serial is usually the volume name I assume it will not work if you rename the USB device in between?
Guess I have to use the new name then instead of the serial.

[euklides]

I think "serial" and "volume name" are not the same thing... Or not ?

I did the test: changing the volume name does not change the serial !

[RhoSigma]

Well that's good to know. Not home now, otherwise I had test it myself :)

Thanks, there's certainly a good use for this in any projects.

[Pete]

In 1990-something, I used to use QBASIC error trapping and go through drive letters D-Z, until the drive was discovered. In my old 486 Win 3.1, I used to detect the A or B floppy drive, using a similar alphabetical trapping method. Ah, 1.44 megabytes of memory, all that anyone would ever need!

Pete

[Petr]

I wonder if this nice and useful code will be added to the "toolbox"  here in the forum!

[Pete]

I haven't seen Bill "The Toolbox" Static in ages.

Pete