# C

C support is available natively in Zed.

- Tree-sitter: [tree-sitter/tree-sitter-c](https://github.com/tree-sitter/tree-sitter-c)
- Language Server: [clangd/clangd](https://github.com/clangd/clangd)

## Clangd: Force detect as C

Clangd out of the box assumes mixed C++/C projects. If you have a C-only project you may wish to instruct clangd to all files as C using the `-xc` flag. To do this, create a `.clangd` file in the root of your project with the following:

```yaml
CompileFlags:
  Add: [-xc]
```

By default clang and gcc by will recognize `*.C` and `*.H` (uppercase extensions) as C++ and not C and so Zed too follows this convention. If you are working with a C-only project (perhaps one with legacy uppercase pathing like `FILENAME.C`) you can override this behavior by adding this to your settings:

```json
{
  "file_types": {
    "C": ["C", "H"]
  }
}
```

## Formatting

By default Zed will use the `clangd` language server for formatting C code. The Clangd is the same as the `clang-format` CLI tool. To configure this you can add a `.clang-format` file. For example:

```yaml
---
BasedOnStyle: GNU
IndentWidth: 2
---
```

See [Clang-Format Style Options](https://clang.llvm.org/docs/ClangFormatStyleOptions.html) for a complete list of options.

You can trigger formatting via {#kb editor::Format} or the `editor: format` action from the command palette or by adding `format_on_save` to your Zed settings:

```json
  "languages": {
    "C": {
      "format_on_save": "on",
      "tab_size": 2
    }
  }
```

See [Clang-Format Style Options](https://clang.llvm.org/docs/ClangFormatStyleOptions.html) for a complete list of options.

## Compile Commands

For some projects Clangd requires a `compile_commands.json` file to properly analyze your project. This file contains the compilation database that tells clangd how your project should be built.

### CMake Compile Commands

With CMake, you can generate `compile_commands.json` automatically by adding the following line to your `CMakeLists.txt`:

```cmake
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
```

After building your project, CMake will generate the `compile_commands.json` file in the build directory and clangd will automatically pick it up.