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[luisgutierrezb]

De nuevo de la ayuda de Win32 Programmer's Reference

The GetWindowText function copies the text of the specified window's title bar (if it has one) into a buffer. If the specified window is a control, the text of the control is copied.

int GetWindowText(
HWND hWnd, // handle of window or control with text
LPTSTR lpString, // address of buffer for text
int nMaxCount // maximum number of characters to copy
);


Parameters
hWnd
Identifies the window or control containing the text.
lpString
Points to the buffer that will receive the text.
nMaxCount
Specifies the maximum number of characters to copy to the buffer. If the text exceeds this limit, it is truncated.

Return Values
If the function succeeds, the return value is the length, in characters, of the copied string, not including the terminating null character. If the window has no title bar or text, if the title bar is empty, or if the window or control handle is invalid, the return value is zero. To get extended error information, call GetLastError.