How to read a registry entry

Hi,

I am new to C++ and I am struggling to understand something you guys probably take for granted!

I need to write some code to take in a registry key....for example

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Nls\CodePage\ACP

and return the String value...in this case 1252.

Now I am struggling with the GetStringValue function, could someone show me an example of how this can be done?

Cheers

Pete

*cough* MSDN you freak!! *cough*

Code:

//#define UNICODE //Uncomment for unicode build (Faster on NT/XP)
//#define _UNICODE//Uncomment for unicode build (Not for Win95/98)
#include <windows.h>
#include <tchar.h>


int WINAPI WinMain(HINSTANCE hInst,
				   HINSTANCE,LPSTR,int){

	const int cBuffSize = 255;//Size of buffer
	TCHAR szBuff[cBuffSize] = {0},//Actual buffer
		  *szPath = //Path of key
		_T("SYSTEM\\CurrentControlSet\\Control\\Nls\\CodePage");
	HKEY hKey = NULL;//Key used to hget value
	DWORD dwSize = cBuffSize; //To tell buff size and recieve actual size
		 

	//First open a key to allow you to read the registry
	if(RegOpenKeyEx(HKEY_LOCAL_MACHINE,//Main key to browse
		            szPath,//sub key
					0,
					KEY_READ,//access rights - we want to read
					&hKey)//Recieve the key we want to use
					!= ERROR_SUCCESS){
		MessageBox(HWND_DESKTOP,_T("Could not open key"),NULL,MB_OK);
		return 1;
	}

	if(RegQueryValueEx(hKey,//From previous call
					   _T("ACP"),//value we want to look at
					   0,
					   NULL,//not needed,we know its a string
					   (UCHAR*)szBuff,//Put info here
					   &dwSize)//How big is the buffer?
					   !=	ERROR_SUCCESS){
		MessageBox(HWND_DESKTOP,_T("Could not get value"),NULL,MB_OK);
		return 1;
	}

	MessageBox(HWND_DESKTOP,szBuff,_T("Result"),MB_OK);

	RegCloseKey(hKey);//Dont forget to cleanup!!!!
		
	return 0;
}

>>*cough* MSDN you freak!! *cough*

Cute!

>>*cough* MSDN you freak!! *cough*

Cute!

I'm just a regular good Samaratin

Rob,

Thanks this is a start! I have moved the code into VC++ and hit compile, but it is complaining about *szPath.

Message I am getting is :

E:\lib\Cpp1.cpp(13) : error C2440: 'initializing' : cannot convert from 'char [46]' to 'unsigned short *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

The line is :

TCHAR szBuff[cBuffSize] = {0},//Actual buffer
*szPath = _T("SYSTEM\\CurrentControlSet\\Control\\Nls\\CodeP age");

Am I doing something wrong here?

Pete

Err....Sorry I may not have made the first part of the code clear.....

There are 2 defines.......for Win95 & win2000/XP leave them both commented....If you want a UNICODE build for windows NT/2000/XP then uncomment them both.......

Sorry, I shouldt have bothered with the unicode stuff at all......got a little carried away in what I was doing......apologies

Sorry Rob, I must be doing something wrong here....

I copy the code into a file called TEST.C and then issue a command cl -c TEST.C from the command prompt.....

I have tried with and without the DEFINE statements, but i still get this message.....


C:\>cl -c test.c
Microsoft (R) 32-bit C/C++ Standard Compiler Version 12.00.8168 for 80x86
Copyright (C) Microsoft Corp 1984-1998. All rights reserved.

test.c
test.c(8) : error C2055: expected formal parameter list, not a type list
test.c(11) : error C2057: expected constant expression
test.c(11) : error C2466: cannot allocate an array of constant size 0

C:\>

I must be doing something daft!

Pete

Hmm...try a normal ANSI build...put this code in and build as normal

Code:

#include <windows.h>



int WINAPI WinMain(HINSTANCE hInst,
				   HINSTANCE,LPSTR,int){

	const int cBuffSize = 255;//Size of buffer
	CHAR szBuff[cBuffSize] = {0},//Actual buffer
		  *szPath = //Path of key
		"SYSTEM\\CurrentControlSet\\Control\\Nls\\CodePage";
	HKEY hKey = NULL;//Key used to hget value
	DWORD dwSize = cBuffSize; //To tell buff size and recieve actual size
		 

	//First open a key to allow you to read the registry
	if(RegOpenKeyEx(HKEY_LOCAL_MACHINE,//Main key to browse
		            szPath,//sub key
					0,
					KEY_READ,//access rights - we want to read
					&hKey)//Recieve the key we want to use
					!= ERROR_SUCCESS){
		MessageBox(HWND_DESKTOP,"Could not open key",NULL,MB_OK);
		return 1;
	}

	if(RegQueryValueEx(hKey,//From previous call
					   "ACP",//value we want to look at
					   0,
					   NULL,//not needed,we know its a string
					   (UCHAR*)szBuff,//Put info here
					   &dwSize)//How big is the buffer?
					   !=	ERROR_SUCCESS){
		MessageBox(HWND_DESKTOP,"Could not get value",NULL,MB_OK);
		return 1;
	}

	MessageBox(HWND_DESKTOP,szBuff,"Result",MB_OK);

	RegCloseKey(hKey);//Dont forget to cleanup!!!!
		
	return 0;
}

Rob,

Still no joy....

C:\>cl -c test.c
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8168 for 80x86
Copyright (C) Microsoft Corp 1984-1998. All rights reserved.

test.c
test.c(6) : error C2055: expected formal parameter list, not a type list
test.c(9) : error C2057: expected constant expression
test.c(9) : error C2466: cannot allocate an array of constant size 0

Not sure if there is something I am doing wrong!

Pete

Right...I gotcha......My code uses a few of the tricks C++ allows, but are not allowed in straight C

• I use a const int to size an array - big nono in C
• I dont explicitly state the params recieved in WinMain - big nono in C
• I set the array to zero with = {0} - not in C thank you!

So, compile my code in C++, or do this...

Code:

#include <windows.h>

#define cBuffSize 255//Size of buffer



int WINAPI WinMain(HINSTANCE hInst,
				   HINSTANCE phInst,LPSTR lps,int nShow){




	CHAR szBuff[cBuffSize],//Actual buffer
		  *szPath = //Path of key
		"SYSTEM\\CurrentControlSet\\Control\\Nls\\CodePage";
	HKEY hKey = NULL;//Key used to hget value
	DWORD dwSize = cBuffSize; //To tell buff size and recieve actual size


	//First open a key to allow you to read the registry
	if(RegOpenKeyEx(HKEY_LOCAL_MACHINE,//Main key to browse
		            szPath,//sub key
					0,
					KEY_READ,//access rights - we want to read
					&hKey)//Recieve the key we want to use
					!= ERROR_SUCCESS){
		MessageBox(HWND_DESKTOP,"Could not open key",NULL,MB_OK);
		return 1;
	}

	if(RegQueryValueEx(hKey,//From previous call
					   "ACP",//value we want to look at
					   0,
					   NULL,//not needed,we know its a string
					   (UCHAR*)szBuff,//Put info here
					   &dwSize)//How big is the buffer?
					   !=	ERROR_SUCCESS){
		MessageBox(HWND_DESKTOP,"Could not get value",NULL,MB_OK);
		return 1;
	}

	MessageBox(HWND_DESKTOP,szBuff,"Result",MB_OK);

	RegCloseKey(hKey);//Dont forget to cleanup!!!!

	return 0;
}

Just woke me up to how un-C-friendly my code has now become....

Rob,

Many many thanks!!!

I should have stated that it had to be C and not C++.

I used the code in C 10 years ago, and I am very rusty! I have been using Advantage:Gen from CA for ages and the external code we need to write had to be in Ansi C.

Thank you for the clear code and comments, I think I understand now!!

Cheers

Pete