How to open a .c file (Windows, Mac, Linux)

Q: Why can't I open my .c file?

Usually your computer lacks an app that understands C. Install one of the apps listed here, or convert the file to a more common format.

A .c file is a C Source File. If double-clicking does nothing, your computer simply does not have an app that reads C yet. Here is how to fix that on each operating system, using free software wherever possible.

Open a .c file step by step

Confirm the file really is a .c. Drop it into the WhatFileType file identifier, which reads its signature without uploading anything.
On Windows, open it with VS Code or Visual Studio.
On Mac, use VS Code or Xcode.
On Linux, try VS Code or vim.
Still stuck? Convert the .c to exe (via a compiler), which opens more widely.

Best apps to open .c files

Windows

VS Code
Visual Studio
any text editor

macOS

VS Code
Xcode
any text editor

Linux

VS Code
vim
gcc / clang

Before you open it: Caution. A .c file is program source. Compiling and running it executes its code, so review unfamiliar files first.

Frequently asked questions

Why can't I open my .c file?

Almost always because no installed app understands C. Install one of the apps above, or convert the file to a format your existing software already reads.

How do I compile a .c file?

Use a C compiler: gcc file.c -o program on Linux or Mac, then run ./program. On Windows, Visual Studio or MinGW does the same.

What is the difference between a .c and a .h file?

A .c file holds the actual code. A .h header declares the functions and types so other .c files can use them; headers are included, not compiled on their own.