Right-click main.c in the Projects tab of the Management window and choose Remove File From Project from the context menu that appears.
Code::Blocks removes the file from the project tree.
Choose File→New→File.
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You see the New from Template dialog box shown.
Highlight the C/C++ Header icon and click Go.
You see the Welcome page of the C/C++ Header wizard.
Click Next.
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The wizard asks you to provide the header configuration information.
In the Filename with Full Path field, type MathLibrary.h, click the ellipses button, and then click Save.
Code::Blocks adds the complete project path to the filename you chose. Notice that Code::Blocks also supplies an entry for the Header Guard Word field. This word ensures that the header isn’t added more than once to a project.
Click All, and then click Finish.
The C/C++ Source wizard adds the file to your project. You’re ready to begin creating a template library.