Creating a C/C++ Code Formatting tool with help of Clang tools

Today we are going to discuss formatting files in the user’s workspace by their extension. For this we are going to make use of Clang’s format tools.


  • Linux Machine
  • Python
  • Clang Tool


  • Install Python using the following command:
    sudo apt-get install python
  • Install Clang Format Tools
    sudo apt-get install clang-format-3.5
  • Create a python file named format-code.py at any location where you have read and write permissions. In this example we are going to create it in /home/user/. It shall contain the following code:
    # Python program to format C/C++ files using clang-format
    import os
    # File Extension filter. You can add new extension
    cpp_extensions = (".cxx",".cpp",".c", ".hxx", ".hh", ".cc", ".hpp")
    # Set the current working directory for scanning c/c++ sources (including
    # header files) and apply the clang formatting
    # Please note "-style" is for standard style options
    # and "-i" is in-place editing
    for root, dirs, files in os.walk(os.getcwd()):
        for file in files:
            if file.endswith(cpp_extensions):
                os.system("clang-format-3.5 -i -style=file " + root + "/" + file)

  • Create format specification file and copy it to project’s top level directory , e.g., /home/user/myproject/
    1. Create formatting file (in example, we are creating google coding style tool)
      clang-format-3.5 -style=google -dump-config > .clang-format 
    2. Copy it to project’s directory i.e., it’s location becomes: /home/user/myproject/.clang-format

How to use it?

  • Navigate to the directory whose files you want to format, e.g.,
    cd  /home/user/myproject/c-source/
  • Run the format-code file that you created earlier
    python /home/user/format-code.py
  • This shall format all the files in our source directory with the extension same as that mentioned in the code.

    Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

This article is attributed to GeeksforGeeks.org



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