CRegKey

This is a discussion on CRegKey within the Windows Programming forums, part of the Platform Specific Boards category; Hi, I'm wondering about something here. How would you detect if a user has a key value in the registry, ...

  1. #1
    I am the worst best coder Quantrizi's Avatar
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    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)

  2. #2
    train spotter
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    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.
    "Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
    Friedrich Nietzsche

    "I spent a lot of my money on booze, birds and fast cars......the rest I squandered."
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  3. #3
    I am the worst best coder Quantrizi's Avatar
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    Quote Originally Posted by novacain
    try

    "Software\\TriFaze\\Jam MP3"
    Either way works just the same.

    Quote 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.

    Quote 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 **
    Last edited by Quantrizi; 07-06-2004 at 07:03 AM.

  4. #4
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    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)
    "Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
    Friedrich Nietzsche

    "I spent a lot of my money on booze, birds and fast cars......the rest I squandered."
    George Best

    "If you are going through hell....keep going."
    Winston Churchill

  5. #5
    I am the worst best coder Quantrizi's Avatar
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    Quote 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;
    }

  6. #6
    erstwhile
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    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\\
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  7. #7
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    Quote 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.

  8. #8
    erstwhile
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    Try sizeof(char) instead of sizeof(char*) in your fwrite call:
    Code:
    fwrite(text, sizeof(char), strlen(text), fp)
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  9. #9
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    Quote 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?
    Last edited by Quantrizi; 07-09-2004 at 02:39 PM.

  10. #10
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    >>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
    "Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
    Friedrich Nietzsche

    "I spent a lot of my money on booze, birds and fast cars......the rest I squandered."
    George Best

    "If you are going through hell....keep going."
    Winston Churchill

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