# FAQ
## What commands are available?
`new`, `init`, `build`, `run`, `clean`, `gen`, `--help`, `--version`, `--update`.
## Is `dcr.toml` mandatory?
Yes, for `build`, `run`, and `clean`.
## What source files are compiled?
DCR scans `src/` recursively:
- for C: `*.c`
- for C++: `*.cpp`, `*.cxx`, `*.cc`
## Can I switch compiler?
Yes. Set `build.compiler` in `dcr.toml` (for example `gcc`, `clang`, `cl`, `clang-cl`).
## How does incremental rebuild work?
It compares source file mtime with object file mtime.
Header dependencies are tracked too: if an included header changes (or disappears), rebuild is triggered.
## What does `dcr run` do if build fails?
It tries to run an existing binary from the selected profile; if none exists, it reports an error.
## How do I update DCR?
Use `dcr --update` for non-package-managed installs.
If installed through pacman/AUR, update via package manager.