Ridiculous DWORD error (SOLVED - thanks)
Author
DWORD g_num = 0;
g_num--;
if (g_num<0) g_num=5;
PRINT("gnum = ",g_num);
OUTPUT!!!:
gnum = -1
Visual Studio 2005 glitch?
I can't understand why this doesn't work...
Update:
DWORD g_num = 0;
g_num--;
if (g_num<0) g_num=5;
if (g_num==-1) g_num=5
PRINT("gnum = ",g_num);
OUTPUT: gnum = 5
What the heck is going on here?????????? Last time I checked, -1 is less than 0.....
[Edited by - renman29 on April 7, 2007 8:16:34 AM]
Isn't DWORD unsigned? Aren't you using a printf-style function in PRINT to print its value, possibly with the %d directive, which is for signed integers?
DWORD is typedef'd as an unsigned long. So 0 - 1 in unsigned evaluates to 4294967295. Which is certainly not less than 0, so the g_num=5; code is never executred.
also you should try
if ((int)g_num<0)
The DWORD needs to be an int (or some other signed type)for proper conparison and it seems the compiler doesnt do the conversion for you.
if ((int)g_num<0)
The DWORD needs to be an int (or some other signed type)for proper conparison and it seems the compiler doesnt do the conversion for you.
Author
Oh man - I feel completely dumb now.(:p) Thanks very very much. I'll use the (int). Thanks again. (^-^)
Author
A good idea - in this circumstance I need a DWORD var - so what I actually ended up doing was something like this:
Which is basically this sort of anticipation-logic:
if (gnum==0) gnum=5+1;
gnum--; //gnum becomes 5
I can't believe I didn't realize DWORD's unsigned.. I guess what threw me off was the fact that my PRINT function was still saying -1.
I'll stick to int's as much as possible. Thanks. :)
if (g_num<direction_increment) g_num=MY_MAX-(direction_increment-g_num)+direction_increment;gnum+=direction_increment;if (g_num>MY_MAX) g_num=(g_num-MY_MAX);Which is basically this sort of anticipation-logic:
if (gnum==0) gnum=5+1;
gnum--; //gnum becomes 5
I can't believe I didn't realize DWORD's unsigned.. I guess what threw me off was the fact that my PRINT function was still saying -1.
I'll stick to int's as much as possible. Thanks. :)
Quote:Original post by renman29
I guess what threw me off was the fact that my PRINT function was still saying -1.
Then use a better one. (In particular, assuming C++, don't wrap printf-type stuff, because it's not typesafe. Instead, work with iostreams.)
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