Visual C++ basic program error

Question

Hi guys.I'm new in programing and i'm getting this error...

Run-Time Check Failure #3 - The variable 'x' is being used without being initialized.

...in this program

#include<windows.h>

int _stdcall WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow){
    SYSTEM_POWER_STATUS x;
    if (x.BatteryFlag == 8)
     MessageBox(NULL,L"Battery is Charging.",L"Caution!",MB_ICONINFORMATION);
    
}

tell me please,what i'm doing wrong and if this program is able to get know if my laptop battery is charging.thnx.

Answer 1

What do you need as a more detailed explanation? I think "The variable 'x' is being used without being initialized."is a very helpful error message.

Maybe change the line

SYSTEM_POWER_STATUS x;

to this

SYSTEM_POWER_STATUS x;
x=ZeroMemory(&x, sizeof(SYSTEM_POWER_STATUS));

ZeroMemory initialize the structure SYSTEM_POWER_STATUS with zeros.

https://msdn.microsoft.com/en-us/library/windows/desktop/aa366920(v=vs.85).aspx

---

Best regards

Bordon

Note: Posted code pieces may not have a good programming style and may not perfect. It is also possible that they do not work in all situations. Code pieces are only indended to explain something particualar.

Answer 2

i don't still understand that why it was necessary but it worked.

yet it is giving a new error message

'=' : cannot convert from 'void *' to 'SYSTEM_POWER_STATUS'

thnx for reply!

Answer 3

On 1/26/2015 8:49 AM, DkMandar wrote:

     SYSTEM_POWER_STATUS x;
     if (x.BatteryFlag == 8)

How do you expect x.BatteryFlag to acquire the value of 8 (or any other value)? Do you believe the structure will magically fill itself?

The documentation for SYSTEM_POWER_STATUS mentions the function you should use to initialize it.

---

Igor Tandetnik

Answer 4

You first have to call GetSystemPowerStatus( &x ); To set the values for the structure.

Also the BatteryFlag is a bit field that may contain other values so an appropriate check for charging is something like this:

SYSTEM_POWER_STATUS status;
ZeroMemory(&status, sizeof(status));
BOOL result = GetSystemPowerStatus(&status);
if (!result)
{
	// FAILED to get power status
	return -1; 
}
		
bool isCharging = (status.BatteryFlag & 8) != 0;

Answer 5

alright.as u said @Igor Tandetnik,i tried hard.but i'm beginner and still doing something wrong.please identify my mistake.here is code>

#include<windows.h>

int _stdcall WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow){
    SYSTEM_POWER_STATUS status;
    GetSystemPowerStatus(&status);
    if(status.BatteryFlag == 8)
    MessageBox(NULL,L"Battery is charging",L"caution",MB_ICONINFORMATION);
    
}

Answer 6

its not working @Wyck.giving an error that illegal use of data type BOOL in an expression.

thnx for reply anyway!

 

Answer 7

SomeOne help me please...

Answer 8

What isn't working?  Is the compiler giving error messages (what is the message, what line?)

Does the code not do what you expect?  If you use the debugger and put a breakpoint on your if statement, what value does status.BatteryFlag have?

Answer 9

@SimonRev,

@ Wyck

program is supposed to show an massage of "battery is Charging",when i connect it to adapter.but instead it is showing these lines in output window...

'Learning_first.exe': Loaded 'C:\Users\DkMandar\Documents\Visual Studio 2010\Projects\Learning_first\Debug\Learning_first.exe', Symbols loaded.
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\ntdll.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\kernel32.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\KernelBase.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\user32.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\msvcr100d.dll', Symbols loaded.
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\gdi32.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\imm32.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\msctf.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\msvcrt.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\Jaksta\AC\x86\jaudcap.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\advapi32.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\ole32.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\sechost.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\rpcrt4.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\combase.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\sspicli.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\cryptbase.dll', Cannot find or open the PDB file
'Learning_first.exe': Loaded 'C:\Windows\SysWOW64\bcryptprimitives.dll', Cannot find or open the PDB file
1144) CheckProcessInRegistry: Got include list but no match was found.
1144) IsProcessAllowed(C:\Users\DkMandar\documents\visual studio 2010\Projects\Learning_first\Debug\Learning_first.exe) (80004005)
1144) DllMain(ProcDetach) [OK]
1144) DSound_Unhook
1144) MCIWave_Unhook
1144) AudioClient_Unhook
1144) CAudioStreamMgr::Shutdown
'Learning_first.exe': Unloaded 'C:\Windows\Jaksta\AC\x86\jaudcap.dll'
'Learning_first.exe': Unloaded 'C:\Windows\SysWOW64\combase.dll'
'Learning_first.exe': Unloaded 'C:\Windows\SysWOW64\sechost.dll'
'Learning_first.exe': Unloaded 'C:\Windows\SysWOW64\rpcrt4.dll'
'Learning_first.exe': Unloaded 'C:\Windows\SysWOW64\sspicli.dll'
'Learning_first.exe': Unloaded 'C:\Windows\SysWOW64\cryptbase.dll'
'Learning_first.exe': Unloaded 'C:\Windows\SysWOW64\ole32.dll'
'Learning_first.exe': Unloaded 'C:\Windows\SysWOW64\advapi32.dll'
The program '[4420] Learning_first.exe: Native' has exited with code 1 (0x1).

and doing nothing else!

thnx for ur reply.

Answer 10

its not working @Wyck.giving an error that illegal use of data type BOOL in an expression.

thnx for reply anyway!

 

My code worked for me:

#include <windows.h>
#include <iostream>

int main()
{
	SYSTEM_POWER_STATUS status;
	ZeroMemory( &status, sizeof( status ) );
	BOOL result = GetSystemPowerStatus( &status );
	if( !result )
	{
		// FAILED to get power status
		return -1;
	}

	bool isCharging = (status.BatteryFlag & 8) != 0;
	std::cout << "Charging: " << std::boolalpha << isCharging << std::endl;
	return 0;
}

And your code compiles too:

#include<windows.h>

int _stdcall WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow){
    SYSTEM_POWER_STATUS status;
    GetSystemPowerStatus(&status);
    if(status.BatteryFlag == 8)
    MessageBox(NULL,L"Battery is charging",L"caution",MB_ICONINFORMATION);
    
}

So there's something you're not telling me.

What code are you compiling?  What was the error message?  What version of VC are you using?

Answer 11

output shows some lines in output window when i compile MY code.and i told already which lines.

i'm using VC++ 2010.

Answer 12

Does status.BatteryFlag == 8?  What value does it have?

You don't check the error code from GetSystemPowerStatus so I have no idea whether that call failed or succeeded.

You also don't handle the case that status.BatteryFlag == 9.  This would be the case that the battery is charging and contains more than 66%.  You also don't handle 10 or 12, or potential future cases that haven't been defined yet.  You really want

if(status.BatteryFlag & 8)
    MessageBox(NULL,L"Battery is charging",L"caution",MB_ICONINFORMATION);

But put a breakpoint on the if statement and look for yourself at what status is.

Answer 13

yep u r right @SimonRev. it was not battery flag status 8.thats why it was not showing msg.so i used ACLineStatus instead, and it worked. here is code>

#include<windows.h>

int _stdcall WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow){
    SYSTEM_POWER_STATUS status;
    GetSystemPowerStatus(&status);
    if(status.ACLineStatus == 1)
    MessageBox(NULL,L"Battery is charging",L"caution",MB_ICONINFORMATION);
    
}

it shows a msg if adapter is connected.now i need to work to upgrade this program to show a msg when battery get fully charged. u guys were right too @Igor Tandetnik, and @Wyck.thank u all guys for helping me.