Appendix – C

title: Appendix

C: An Appendix

Because C is such a low-level language, there are a lot of terms that come up that aren’t found in a lot of other languages. Here’s an appendix to making understanding them easier.


The compilation is the process of taking the human-readable code and turning it into machine-readable code. This process is performed by a compiler.


A compiler is a program that compiles code, meaning it changes it from something human-readable into something machine-readable.


Debugging is the process of removing errors (“bugs”) from your code. A debugger is a helpful tool that makes that easier.


GNU+Linux is the technically accurate term for what is commonly referred to as “Linux”. Linux is a kernel- it’s a set of programs that allow software to interact with hardware. When combined with GNU, it becomes an operating system, which allows a person to interact with it.


Graphical User Interface. A GUI will allow you to interact with a program by pointing and clicking rather than having to type in commands.

Header Files

Header files are files containing function declarations that are defined in other source files. These are typically ‘included’ at the top of a source file.


The human-readable code is code that can be read by a person- it’s not in binary or machine code.


Integrated Development Environment. This is mostly an editor but includes tools to check syntax, format code style, compile, and debug a program, which makes writing code easier.


Libraries are useful sets of code that give more functions and features in the language.


A piece of Software that combines multiple Object files (usually compiled source code or libraries) into one executable file. Another name for the Linker is a ‘Loader’.

Low-Level language

A low-level programming language contains binary or assembly code which has little or no abstraction from machine level instructions.

Machine Code

Machine code is the code that the machine can understand. Remember that computers use numbers, not English, to run.


A newline is what gets printed when you hit Enter, and is an example of a whitespace character. You can also add a newline to the output of your program by including ‘\n’ in your print statement.

Object File

A file that contains Object Code (Machine Code). The file contains output some compilation, meaning it will contain machine code/assembly code.


A pointer is a variable that contains the memory address of another variable. Arrays, Structures and Functions explicitly use pointers which can help produce efficient and easy-to-read code.

Source Code

Source code is any collection of code, possibly with comments, written using a human-readable programming language, usually as plain text. The source code is often transformed by an assembler or compiler into binary machine code understood by the computer.


Whitespace is the characters that you don’t see when you type but are there anyway. For example, you can’t see spaces, but there is a lot here. Newlines are also whitespace characters, as are tabs.

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