右键单击 -> properties -> C/C++ General -> Paths and Symbols -> Add… -> file system.
Eclipse reports Unresolved inclusion for system headers such as stdio.h if it cannot locate the header files for a project. You can resolve this by right-clicking on the project in the Project Explorer view and then selecting Properties… from the context menu. In the dialog box, select: C/C++ General → Paths and Symbols → Add… and then add the path to the ARM Compiler headers on your host workstation. For example, C:Program FilesDS-5include. Select both Add to all configurations and Add to all languages, click on Apply so that Eclipse can rebuild the index.