Get letter drives

[MPrestonf12]

im trying to get each drive on my computer. Is their a way to do this? Right now im just having it loop through four times for each drive on my computer but i want it to be portable for other computers with more or less drives.


char buff[10];
int i;

for(i=0;i<4;i++){

GetLogicalDriveStrings(10,buff);

MessageBox(NULL,buff,"dd",MB_OK);
}


this only return "A:/ "four times though.
thanks

[parksie]

#include <windows.h>
#include <math.h>
#include <stdio.h>

BOOL is_drive(char letter, unsigned long drives) {
return drives & (unsigned long)pow(2, letter - 'A');
}

int main(void) {
unsigned long drvspec = GetLogicalDrives();

for(char i = 'A'; i <= 'Z'; ++i) {
if(is_drive(i, drvspec)) {
printf("Drive %c\n", i);
}
}

return 0;
}

[MPrestonf12]

Parksie, do you mind explaining breifly how that works. Thanks

[parksie]

GetLogicalDrives returns an unsigned long (DWORD), where drive A is bit 0, drive B is bit 1, etc.

If they're set, the drive exists. So what that does is just to check through all of them seeing if the corresponding bit is set. I suppose I could drop the call to pow and use a shift (quicker, but I can't remember which way round it is for Intel).

[MPrestonf12]

im not sure why but I get a illegal operation whenI try and run it.

[parksie]

Works fine for me...

[MPrestonf12]

sorry, your code was right but here was the problem.


SendMessage(drvlstS,LB_ADDSTRING,0,(LPARAM)i);


do you know why I can't set that string?

[parksie]

Because i is only a single character.char buf[2] = { i, 0 };

SendMessage(drvlstS,LB_ADDSTRING,0,(LPARAM)buf);

[MPrestonf12]

Thanks alot Parksie!

[parksie]

No probs :)

Oh yeah, anything that goes into that function must be upper case or it won't work.

[CornedBee]

Another version of parksies function:

// add this include
#include <ctype.h>
// and for debug purposes
#include <assert.h>

BOOL is_drive(char letter, unsigned long drives) {
assert(isalpha(letter));
return drives & (1 << (toupper(letter) - 'A'));
}


I'm pretty sure that left shift is right, but you must try. If it doesn't work correctly, try
0x80000000 >> (toupper(letter) - 'A')
or stick to parksies way.