Thread: Help with RegQueryValueEx

I'll try to read com port value from the register with following code.
I don't get a value , could somebody help?

--------------------------

Code:

    HKEY    myKey;
    BYTE*   valData;
    DWORD   valDataSize;
     
	if (RegOpenKeyEx (HKEY_LOCAL_MACHINE, "HARDWARE\\DEVICEMAP\\SERIALCOMM\0", 0, KEY_QUERY_VALUE, &myKey)
        != ERROR_SUCCESS)
    {
        printf ("\nCould not open key.");
       
    }   
    valData = (BYTE*)malloc (4);
    valDataSize = 1024;
    if (RegQueryValueEx (myKey, "Device\\Serial0\0", NULL, NULL, valData, &valDataSize)
        != ERROR_SUCCESS)
    {
        printf ("\nCould not query integer value.");
        
    }  
    printf("\nHistoryListLength: %d", *valData);    
        
	
    if (RegQueryValueEx (myKey, "Device\\Serial0\0", NULL, NULL, NULL, &valDataSize) 
	!= ERROR_SUCCESS)
    {
        printf ("\nCould not query string size.");
       
    } 
    
    
    valData = (BYTE*)realloc (valData, valDataSize);
    if (RegQueryValueEx (myKey, "Device\\Serial0\0", NULL, NULL, valData, &valDataSize) 
	!= ERROR_SUCCESS) 
    {
        printf ("\nCould not query string value.");
        
    }
    printf ("\nUserName: %s", valData);
    
    

    free (valData);
    RegCloseKey (myKey);

Originally Posted by Salem

> valData = (BYTE*)malloc (4);
> valDataSize = 1024;
How is allocating 4 bytes, then saying you've got 1024 bytes going to help?
That's 1020 bytes trashed over someone else's memory.

Sorry, right value is 4, that 1024 is just typo.

Typo,blackout, whatever when I wrote it. I'm terrible sorry.

Like John Lennon sang:

I didn't mean to hurt you
I'm sorry that I made you cry...