File types

• C++ declarations are stored in text files with extension .h (header files)
• C++ source code is stored in text files with extension .cxx
• Executable files have no extensions but their ``executable'' property is set to on (e.g. ls -la /bin/bash returns 'x' in the properties field)
• Each executable must have exactly one symbol main corresponding to the first function to be executed
• An executable can be obtained by compiling many source code files (.cxx), exactly one of which contains the definition of the function int main(int argc, char** argv);, and linking all the objects together
• Source code files are compiled into object files with extension .o by the command
  c++ -c sourceCode.cxx