A C file is a source code file for a C or C++ program. It may include an entire program's source code, or may be one of many source files referenced within a programming project. C files can be edited using a basic text editor, but will not show syntax highlighting like most software development programs do.
C file open in Microsoft Visual Studio Code 1.33
C++ is an extension of the C programming language and was released in the mid-1980s. It is used for creating many of today's software programs and may be stored in C, .CC, .CPP, .CXX, and .C++ source code files.
NOTE: Some Unix compilers use a lowercase ".c" extension for C and an upper case ".C" extension for C++, although this convention is not common.