Many new MFC programmers wonder how to 'replace' the default icon rather than to change or edit in the resourc editor. Here are two simple ways to do this (actually one method but two versions).
1. There is an ICON statement in the resource (.rc) file that causes the resource compiler to include the icon in the program's resources. The default icons for MFC projects are placed in ../res folder. To replace these icons we need to edit rc file and supply new icons for the existing ones. Proceed as follows:
(i). copy the new icon file in .../res folder. This step is not essential but its better to put all the resources in one folder.
(ii). Select File -> Open and File Open Dialog popups. Select the rc file and change the 'open as' combo box to 'text' (which is 'auto' by default) in the File Open Dialog box. Now Look for the ICON statement in rc file, which should look like:
Next simply change the concerned file name with new one, e.g:
// Icon with lowest ID value placed first to ensure
// application icon remains consistent on all systems.
IDR_MAINFRAME ICON DISCARDABLE "res\\Project.ico"
IDR_DEVICETYPE ICON DISCARDABLE "res\\ProjectDoc.ico"
Now build the project and the new icon should show up.
IDR_MAINFRAME ICON DISCARDABLE "res\\NewIcon.ico"
2. The second way is the short-cut version of the first. Instead of editing the rc file just rename the new icon to the same old icon name and copy onto it. However if you build your project, the same old (default) icon will be shown though it does not even exist on the disk now! This is because the resource compiler does not detect any changes in rc file and hence it doesn't actually recompile the rc file (unless some change is introduced into it). As a result the program shows the same old icon which was added to it in the last compilation. Hence to take the effect, just recompile the rc file. It can simply be done by opening it as a text file (as in method 1), click in the file and compile (Ctrl+F7).
Note: Its generally not recommended to manually edit rc file, however there is no harm with the above procedures and can be used without any fear.