Char* to registry, then retrieve it?

[Adam01]

Hi, I have been doing some work involving the registry.
I can write and read numbers fine, but im stuck writing and reading strings.

I've been googling for a while, and found mostly references to vc.

So basicly, can someone explain to me how to write a char* to a registry key, and then retrieve it again, into char* form.

[JosAH]

Maybe this link helps?

kind regards,

Jos

[Adam01]

Ah, I was using regQueryValueEx, thanks for the link, I looked around and found:
"To ensure that any string values (REG_SZ, REG_MULTI_SZ, and REG_EXPAND_SZ) returned are null-terminated, use the RegGetValue function."

I had a go at using RegGetValue, but including windows.h, and winreg.h, the compiler says it has not been defined. Any ideas?

[Li2Ti]

@Adam01
RegGetValue is a relatively new function. You'll need to set _WIN32_WINNT to >= 0x600 in order to use it.

[Adam01]

Thanks, but still no luck...

[Li2Ti]

@Adam01
You are defining it before you include the Windows header, right?

[Adam01]

Yes, as well, the compiler says it is redefined.

[Li2Ti]

@Adam01
And what version of Windows are you compiling this under?

[Adam01]

Windows xp media center, with sp3.

[Li2Ti]

@Adam01
There's your problem. That function isn't supported on your OS.

Anyway, what's wrong with RegQueryValueEx? IIRC, it's been supported since Win2k.

Just be careful with string termination and you should be alright.

[Adam01]

I am using it with wxWidgets,
this is the current code...

DWORD StrSize = sizeof(char*);
DWORD SZTHING = REG_SZ;
char* tempusername;
RegQueryValueEx(hKey, TEXT("UsernameValue"), NULL, &SZTHING, (BYTE*)&tempusername, &StrSize );
ConnectSettings->Username = wxString(tempusername, wxConvUTF8);
wxMessageBox( ConnectSettings->Username , _("Note"));

This would cause the program to crash.
Yes, I am not familiar to registry functions.

[Li2Ti]

@Adam01
Not surprising.

1. Don't ignore API return codes.
2. Look at where RegQueryValueEx is trying to write to.
3. MSDN is your friend.

[Adam01]

Thanks, I found out that it was the value, written by:

const char *Username = ConnectSettings->Username.mb_str();
RegSetValueEx (hKey, TEXT("UsernameValue"), 0L, REG_SZ,(CONST BYTE*) &Username, sizeof(REG_SZ));

Which writes incorrect value.

I'l have a look at the return codes.

[Adam01]

Both return success (0),
If I set the key to "hello", the program does not crash, but displays nothing.

[Li2Ti]

@Adam01
Re-read post No. 12.

Where do you think the RegQueryValueEx function is attempting to write to?

Also, there are countless examples of this sort of thing on the Internet.

[Adam01]

1. RegQueryValueEx is not writing, it is reading.

And I have now solved it, using TCHAR instead of char.

[Li2Ti]

@Adam01
It writes to the buffer that you pass. That's the whole point...