clang-format-3.9 software package provides Tool to format C/C++/Obj-C code, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install clang-format-3.9
clang-format-3.9 is installed in your system.
Make ensure the clang-format-3.9 package were installed using the commands given below,
$ sudo dpkg-query -l | grep clang-format-3.9 *
You will get with clang-format-3.9 package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Development |
| Package | clang-format-3.9 |
| Version | 1:3.9-4 |
| Description | Tool to format C/C++/Obj-C code |
| Sub Section | devel |