Rotating Screen Probably Simple Fix

[Always]

I am brand new to C infact i just started learning it yesterday.

I have no idea what i'm doing wrong. i found this bit of code on the internet somewhere and it's telling me one of the constant variables which should have come with the windows.h header (i think) is undeclared.

here is the code:

//Flip screen
void flipScreen(void)
{
     // Get current Device Mode.
     DEVMODE DeviceMode = { 0 };
     EnumDisplaySettings( NULL, ENUM_CURRENT_SETTINGS, &DeviceMode );

     //Change display mode upside down.
     DeviceMode.dmDisplayOrientation = DMDO_180;
     ChangeDisplaySettings( &DeviceMode, 0 );

     // Sleep for 10 seconds.
     Sleep( 10000 );

     // Change display mode back.
     DeviceMode.dmDisplayOrientation = DMDO_DEFAULT;
     ChangeDisplaySettings( &DeviceMode, 0 );

}

Here is what my compilier is telling me:

In function 'flipScreen':
'DMDO_180' undeclared (first use in this function)
(Each undeclared identifier is reported only once
for each function it appears in.)
'DMDO_DEFAULT' undeclared (first use in this function)
[Build Error] [main.o] Error 1

[CommonTater]

Ok... if you are THAT new to C... you need to learn the language before you start messing with stuff that could potentially cause you problems with your system... ESPECIALLY... DeviceMode settings.

Start here... Teach Yourself C in 21 Days -- Table of Contents go through it page by page, type up the exercises, mess with the code, work the quizzes, repeat as necessary... then, when you finish this introductory tutorial, find an advanced book and do the same study practice with it.

If you study hard and learn well... you *might* be ready for Windows API programming in 6 months to a year...

[Always]

Well thank you for that source i'll be sure to check it out

Any ideas at the question at hand though?

[CommonTater]

Well thank you for that source i'll be sure to check it out

Any ideas at the question at hand though?

I just gave them to you... Don't even think about trying that kind of stuff yet... You'll regret it.

You will NOT learn C by copying code from the internet... but you can seriously mess up your system that way.

[AndrewHunter]

Are you developing for a tablet PC? That is the only place I have seen code like that. I am not sure what header files the constants are contained in but they are just literals. DMDO_DEFAULT = 0, _90 = 1, _180=2, and _270 = 3.

[Always]

Are you developing for a tablet PC? That is the only place I have seen code like that. I am not sure what header files the constants are contained in but they are just literals. DMDO_DEFAULT = 0, _90 = 1, _180=2, and _270 = 3.

Yeah, that's what I thought. I tried replacing those literals with integer values, from 0 to 3 and it had no effect on my screen whatsoever.

hmmm...

[claudiu]

Do yourself a favour and take the suggestion provided to actually learn the language before you try to use the windows libraries to do complex tasks. The worst thing that could happen is not that you would mess up your system, but that you might actually get this working, and then think you are ready to be a programmer.

[AndrewHunter]

Again, are you programming for a table PC? Here is the MSDN link Be wary of just scooping code fragments from the internet and trying to use them. It often isn't what you are looking for.

[CommonTater]

Are you developing for a tablet PC? That is the only place I have seen code like that. I am not sure what header files the constants are contained in but they are just literals. DMDO_DEFAULT = 0, _90 = 1, _180=2, and _270 = 3.

Actually it's DMO (Dee Emm Ohh) not DM0 (Dee Emm Zero)...

Given that he's not correctly intializing the DEVMODE structure, the SetDisplayMode call is likely failing and since he's not checking the return value he has no way of knowing that.

But it's a good thing it is failing... If the first call worked and the second failed, he'd be screwed.

[CommonTater]

Do yourself a favour and take the suggestion provided to actually learn the language before you try to use the windows libraries to do complex tasks. The worst thing that could happen is not that you would mess up your system, but that you might actually get this working, and then think you are ready to be a programmer.

And wouldn't THAT be fun!

Yestrday I coun't spel "Prigramer".. today I are one!

[AndrewHunter]

And wouldn't THAT be fun!

Hey, if you are willing to take random code segments that you find and run them without knowing what they do........What is the saying, "In for a penny, in for a pound"

[CommonTater]

OP... post your entire program, please... I'd like to see how you're calling that function.