Editing General Geant4 Overview (section)

===Understanding the File System===

There are two folders that contain all the files for a Geant4 program, one carries the program name (<example>) and one that carries the program's name hyphenated with build (<example>-build). I will call these the program folder and the build folder respectively from here on. When creating classes and other types of files it is important to know which of these folders should contain them. 

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'''The Program Folder (<example>)'''

All files in this folder get compiled, and if changes are made to any of them the program should be recompiled. There are typically two sub folders called src (meaning source) and include as well as some additional files found in the program folder. 

''src'' - This folder contains all the class files for the program except the main. These files are discussed in more detail later, but any additional classes should be added here. 

''include'' - This folder contains all the header files for the classes in the source folder. There should be a header for each source file created.

''the main class'' - This file is the main class for a simulation. It should have the same name as the project (<example>.cc), and will not have an associated header file. The file will be discussed in greater detail later.

'''The Build Folder (<example>-build)'''

All files in this folder can be edited at any time without having to recompile. Any files not directly associated to the simulation (ROOT macros, data files, etc.) should be saved in this build folder. There is a sub folder called CMakeFiles that contains files necessary to the compiler, and they should not be edited or moved.

''the executable file'' - After compilation, this file is created in the build folder. It cannot be read, but it will run the simulation.

''input files'' - These files can be used to manipulate variables between runs. This technique is discussed in detail on another page. These files can have arbitrary names (<example>.ini), and multiple input files can be created for any project.

''run macros'' - These files are used to run the simulation in batch mode. This technique is discussed in detail later. These files can have arbitrary names (<example>.mac), and multiple macros can be created for any project.