CODEWITHSUNDEEP
winapi
Archimaredes
Archimaredes

Reputation: 1427

What is the maximum length of a window title passed to SetWindowText?

The SetWindowText function's documentation does not set a limit on the length of the string that may be used as a window title.

In the documentation for WM_SETTEXT (the message sent by calling SetWindowText), it is noted that the return value of this message's processing may be:

FALSE (for an edit control), LB_ERRSPACE (for a list box), or CB_ERRSPACE (for a combo box) if insufficient space is available to set the text in the edit control.

However, it says nothing about the case when a window's title is being set. Is a strict limit set, or is it up to the programmer to use common sense to provide their own title length limit?

I have posted this because I am developing a graphics engine which allows the user to supply their own title for the main window. The idea is that I would define a constant such as

const static int MAX_APP_TITLE_LENGTH = /* ??? */;

within my application class, and check the length of the user-provided title string against this.

If the title string is too long, I can throw a warning message and truncate it, rather than passing it straight into SetWindowText with unintended consequences.

EDIT: After some discussion in the comments, it seems that Windows will not complain even if a string of length 100,000 is used as a window title, so this issue is not worth worrying about (beyond the basic sanitization of input, of course)!

Upvotes: 13

Views: 5856

Answers (2)

Terry Morris
Terry Morris

Reputation: 11

If we are talking about a standard windows title, it appears that you can set any length you want using SetWindowText without error. GetWindowText will also return whatever title you have set. Unfortunately, only 255 characters will be shown in the window title bar!

Upvotes: 1

RandomMemer21
RandomMemer21

Reputation: 31

There is technically no limit to the title size, but the lpClassName field has a strict limit of 256 chars (i didnt want you to think you could have an infinite class name and your code crash.)

SOURCE: https://learn.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-wndclassexw

Upvotes: 3

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