Thread: CRegKey

Hi, I'm wondering about something here. How would you detect if a user has a key value in the registry, and if it's not there, create one? The code (at end of post) a friend of mine and me are using doesn't do this. What it does is crash if the m_hKey is NULL.

Code:

		m_regApp.Create(HKEY_CURRENT_USER, "Software\\TriFaze\\Jam MP3\\");

		if(m_regApp.m_hKey == NULL){
			TRACE("Unable to set m_hKey!\n");
		} else{
			TRACE("m_hKey set!\n");
		}

		// Write the new registry settings
	    m_regApp.Open(HKEY_CURRENT_USER, "Software\\TriFaze\\Jam MP3\\");   // Get last saved directory
		m_regApp.SetValue(myMusic, "LastDir");    // Set new directory
		m_regApp.SetValue("255", "LastVolume");    // Set new volume level
		
		if(!m_regApp.QueryValue(drive, "SelectDrive", (DWORD*)&m_dwRead)){
			if(ccd.DoModal() == ID_OK){
				m_regApp.QueryValue(drive, "SelectDrive", (DWORD*)&m_dwRead);
			}
		}

		m_regApp.Close();     // Close the key

(PS: Thanks in advance for any help)

try

"Software\\TriFaze\\Jam MP3"

and

Is the handle NULL before the call to Create() ? If not why not?

then

test the return from the Create() == ERROR_SUCCESS and if not call GetLastError() to find out why.

Originally Posted by novacain

try

"Software\\TriFaze\\Jam MP3"

Either way works just the same.

Originally Posted by novacain

and

Is the handle NULL before the call to Create() ? If not why not?

It seems to be before the call.

Originally Posted by novacain

then

test the return from the Create() == ERROR_SUCCESS and if not call GetLastError() to find out why.

It does return ERROR_SUCCESS.

** EDIT: Added results **

Try an Open(). If that fails then use a Create().

It may be the reg key exists and so the m_hkey is not attatched automatically by the Create() (but the Create() still returns a success because the reg key is there)

Originally Posted by novacain

Try an Open(). If that fails then use a Create().

It may be the reg key exists and so the m_hkey is not attatched automatically by the Create() (but the Create() still returns a success because the reg key is there)

I forgot to add that in to the code I posted above, but it was there.

Anyways though, I decided to do store them in a file, but a new problem arises. When I try to save the directory that was last used, it fails to right the directory (If the directory is C:\Program Files\Pie Is Good\, it'd only save C:\P). Below is the code for it:

Code:

#pragma once

#include <stdio.h>
#include <stdlib.h>

static FILE *fp;

static DWORD dwBytes;

static CString fn;

static BOOL bRW = FALSE;
static BOOL SaveSetting(char *filename, char *text);
static BOOL ReadSetting(char *filename, char *store);

BOOL SaveSetting(char *filename, char *text){
	fn.Empty();
	fn.Format("%s.jp3", filename);

	fp = fopen(fn, "wt");

	if(fp != NULL){
		if(fwrite(text, sizeof(char*), strlen(text), fp) != 1){
			TRACE("fwrite() did not write the file properly!\n");
			AfxMessageBox("fwrite() failed!");

			return FALSE;
		} else{
			TRACE("fwrite() did write the file properly!\n");
			
			return TRUE;
		}

		return TRUE;
	} else{
		TRACE("fp is empty.  No file was opened nor created.\n");
		AfxMessageBox("fp is empty.  No file was opened nor created.");

		return FALSE;
	}

	return TRUE;
}

You should probably modify filename (or fn) to replace '\', which are escape characters, with "\\". For example C:\Program Files\Pie Is Good\ becomes C:\\Program Files\\Pie Is Good\\

Originally Posted by Ken Fitlike

You should probably modify filename (or fn) to replace '\', which are escape characters, with "\\". For example C:\Program Files\Pie Is Good\ becomes C:\\Program Files\\Pie Is Good\\

Well, the way the code works is that the file is created in the same directory as the exe. So, I don't think that's the problem, because the other files are written perfectly.

Try sizeof(char) instead of sizeof(char*) in your fwrite call:

Code:

fwrite(text, sizeof(char), strlen(text), fp)

Originally Posted by Ken Fitlike

Try sizeof(char) instead of sizeof(char*) in your fwrite call:

Code:

fwrite(text, sizeof(char), strlen(text), fp)

Thank you

Why would that make a difference though (it worked though)?

One other thing, now my reading code is causing trouble:

Code:

BOOL ReadSetting(char *filename, char *store){
	fn.Empty();
	fn.Format("%s.jp3", filename);

	fp = fopen(fn, "rt");

	if(fp != NULL){
		if(fread(store, sizeof(char), strlen(store), fp) != 1){
			TRACE("fread() did not read the file properly!\n");
			AfxMessageBox("fread() failed!");

			return FALSE;
		} else{
			TRACE("fread() did read the file properly!\n");
			
			return TRUE;
		}

		return TRUE;
	} else{
		TRACE("fp is empty.  No file was opened nor read.\n");
		AfxMessageBox("fp is empty.  No file was opened nor read.");
	
		return FALSE;
	}

	return TRUE;
}

The problem is that I get the "fread() failed!" whenever I try to read the file. Maybe it has to deal w/ the "!= 1" if statement?

>>Why would that make a difference though (it worked though)?

sizeof(char) != sizeof(char*)


>>if(fread(store, sizeof(char), strlen(store), fp) != 1){


strlen(store) == the number of characters already in store

so if store empty == 0

you want the size of the char array - 1