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Overview |
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Quick Info
Windows NT
| Yes
| Win95
| Yes
| Win32s
| Yes
| Import Library
| -
| Header File
| winuser.h
| Unicode
| No
| Platform Notes
| None
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WM_GETTEXTLENGTH
An application sends a WM_GETTEXTLENGTH message to determine the length, in
characters, of the text associated with a window. The length does not include the
terminating null character.
WM_GETTEXTLENGTH
wParam = 0; // not used; must be zero
lParam = 0; // not used; must be zero
Parameters
This message has no parameters.
Return Values
The return value is the length, in characters, of the text.
Default Action
The DefWindowProc function returns the length, in characters, of the text. Under certain
conditions, this value may actually be greater than the length of the text. For more
information, see the following Remarks section.
Remarks
For an edit control, the text to be copied is the content of the edit control.
For a combo box, the text is the content of the edit control (or static-text)
portion of the combo box. For a button, the text is the button name. For other
windows, the text is the window title. To determine the length of an item in a
list box, an application can use the LB_GETTEXTLEN message.
Under certain conditions, the DefWindowProc function returns a value that is larger than the actual length of the text.
This occurs with certain mixtures of ANSI and Unicode, and is due to the
operating system allowing for the possible existence of DBCS characters within the
text. The return value, however, will always be at least as large as the actual
length of the text; you can thus always use it to guide buffer allocation. This
behavior can occur when an application uses both ANSI functions and common
dialogs, which use Unicode.
To obtain the exact length of the text, use the WM_GETTEXT, LB_GETTEXT, or
CB_GETLBTEXT messages, or the GetWindowText function.
See Also
CB_GETLBTEXT, DefWindowProc, GetWindowText, GetWindowTextLength, LB_GETTEXT, LB_GETTEXTLEN, WM_GETTEXT
Related Links
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More Online Helps
Win32 Multimedia Programmer's Reference (mmedia.hlp)
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Microsoft Windows Telephony API (TAPI) Programmer's Reference (tapi.hlp)
Unix Manual Pages
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