CODEWITHSUNDEEP
c++winapi
Ailef
Ailef

Reputation: 7906

GetWindowText() returning empty string and strange error

I'm using the following code inside a global CBT hook procedure:

TCHAR title[256];
int getT = GetWindowText(hWnd, title, 256);
if (getT == 0) {
    int err = GetLastError();
    logFile << "Error GetWindowText(): " << err << endl;
} else {
    logFile << "getT = " << getT << endl;
}

The problem is that for certain windows the GetWindowText() function works just fine and I get the correct window title, but for some others it returns 0 and I get an empty string. The GetLastError() returns 183 which is ERROR_ALREADY_EXISTS:

Cannot create a file when that file already exists.

The error is not random: I always get it with the same kind of window opened by the same application, but for all the other windows it seems to work fine.

Upvotes: 2

Views: 3869

Answers (1)

Don Reba
Don Reba

Reputation: 14031

You might not have the rights to retrieve text from certain windows on Windows Vista and above.

My guess is that ERROR_ALREADY_EXISTS comes from your log file when you print "Error GetWindowText(): ". You should get the error code first before doing anything else.

Another possibility is that the window returns 0 from its WM_GETTEXT handler without setting the last error. As GetWindowText documentation states, if you call it on a window belonging to the same process, it retrieves the text by sending this message. Since you are calling the function from a hook, you might be in the same process.

Upvotes: 2

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