CMainFrame

CMainFrame is a class name frequently used in applications built with the Microsoft Foundation Class (MFC) library to implement the program’s main frame window. It typically derives from CFrameWnd or CFrameWndEx and serves as the top-level container for the application's user interface, hosting elements such as the menu bar, toolbars, and status bar, and coordinating with the document/view architecture.

In standard MFC SDI or MDI applications, CMainFrame is created early in the application lifecycle and is responsible for initializing and arranging the frame's child controls. Common duties include creating and configuring the menu bar, one or more toolbars, and the status bar; optionally managing docking panes or a rebar; and handling frame-related commands and window messages. The class often overrides PreCreateWindow to set window styles and initial dimensions, and it handles WM_CREATE or related messages to perform control initialization.

CMainFrame interacts with the document and view components by hosting the primary view or views that present the application data to the user. In SDI configurations, it contains the main view; in MDI setups, it may manage an MDI client area and multiple document child frames. The frame window typically processes commands from menus and toolbars via message maps and delegates appropriate actions to the relevant document or view objects.

Variations exist across projects; some code bases rename the class or extend it (for example, CMainFrameEx) or organize it within specialized headers and sources (such as MainFrm.h and MainFrm.cpp). While CMainFrame is a conventional convention in MFC examples, the exact class name, base class, and features can differ depending on the framework version and application design.