Operating Systems and Text Editors Quiz

Chapter 1: Systems Programming and C Basics

• Systems Programming is closely linked to the operating system.
• Basic tools for use with the gcc compiler in a Linux Ubuntu environment (using VirtualBox) are explained.
• Introduction to the C programming language, comparing it with Java syntax.
• Simple programs demonstrating display of information, math calculations, handling random numbers, user input, arrays, and function calls are shown.

1.1 Systems Programming and Operating Systems

• Applications Programming provides services directly to the user, examples include: internet browsers, word processors, games, database access programs, and spreadsheets.

• Systems Programming provides services for other software or the computer system. It does not typically have a Graphical User Interface (GUI) that interacts with the user.

• Examples of systems programs: Firmware (e.g., PC BIOS and UEFI), Operating Systems (e.g., Windows, Mac OSX, GNU/Linux, BSD), Game Engines (e.g., Unreal Engine 4, Unity 3D, Torque3D), Assemblers (e.g., GNU AS, NASM, FASM), Macro Processors (e.g., GNU M4), Linkers and Loaders (e.g., GNU Id which is part of GNU binutils), Compilers and Interpreters (e.g., gcc, Python, Java VM), Debuggers (e.g., gdb), Text editors (e.g., vim), Operating system shell (e.g., bash), Device Drivers (e.g., for Bluetooth, network cards).

• Systems software is at a lower level than application software, often closely tied to the hardware. It uses system calls and provides efficient services to applications.

1.2 Tools for Systems Programming

• Shells: Command-line user interfaces allowing access to operating system services. Examples include sh (Bourne shell), bash (Bourne-again shell), csh (C shell). Shells provide command-line shortcuts and environment variable settings. Also, shells allow programs to run with command-line arguments, options usually preceded by a dash character.

• Text Editors: Programs for creating and editing text-based files, commonly used in C programming are vi/vim, emacs, and gedit.

• Compilers: Software transforming source code into another programming language. In this course, the GNU compiler (GCC) will be used, which is Unix-like in design and free software.

• Debuggers: Tools for testing and debugging other programs, like gdb, to control code execution, view variables and observe execution flow to find out where the program's going wrong or crashing.

1.3 Writing First C Program

• Writing C programs involves creating .c files (Source Code), compiling using gcc to produce .o files (Object Files), linking with libraries to produce an executable file, and ultimately running the executable file.
• Our First Program, a typical "hello world" C program is shown and explained.

1.4 C vs. Java

• Similarities in syntax exist between the two, especially in their commenting features and conditional statements.

• Differences include, C does not need to define the name of a class and the main() function in C returns an integer whereas in JAVA it returns void. Also, the handling of integers, objects, and strings are different, and in C the format string used with the printf function needs explicit flags to be added for each argument.

1.5 Getting User Input

• C uses the scanf() function to get user input, similarly to Java's Scanner class.

• To get input in C, pointers to variables are needed to specify locations in memory where input is stored (this is different from JAVA).

1.6 Functions & Procedures in C

• Functions are crucial for modularizing code for easier maintenance and reusability.
• Function parameters can be: Input data required by a function, Output data the function produces, Input/Output data that is both required and produced by the function.
• Functions are declared and defined before they are used, and passing by value or by reference to a function parameters are possible.

1.7 Coding Conventions/Style

• Variable names should begin with lowercase letters, and additional words capitalized, or using underscores.
• Fixed values like PI, DAYS_IN_YEAR, INTEREST_RATE (all in uppercase letters).
• Use descriptive names for variables for clarity.
• Indentation style is important for code readability.