How to add a C language includePath in my project?

[JARVNM]

I can only include C language std headers, and I don't know how to add a new path to my project. In vscode, I can edit this C/C++ language extension configuration.

[sleeping-at-night]

In this reply, I will assume you don't use build systems like CMake.

There are a few way to config clangd to add include path. One of the simple way is to config clangd via .clangd file.
To do that, simply create .clangd file in your root of your project.
Then let take this folder structure for an example.

projects
├── some_library
│   ├── include
│   │   ├── header1.h
│   │   ├── header2.h
│   │   └── other_header.h
│   └── some_other_files_and_folders
└── your_project
    ├── src
    │   └── main.c
    └── .clangd

You would have something like this in your .clangd file.

CompileFlags:
  Add:
    - "-I/home/path_to_your_projects_folder/some_library/include"

Note: As example shows, I recommended using full path. Relative path may not works as indented.

[mingganglee]

Can I support includePath directly with cmake?

[andyvanee]

Can I support includePath directly with cmake?

Yes, and this use case is called out specifically in the official docs: https://zed.dev/docs/languages/c#cmake-compile-commands