C Programming and C++ Overview

Disadvantages of Programming

• Design, development, and debugging in programming can be very time-consuming.

Overview of C++

• Developed by Bjarne Stroustrup at Bell Laboratories.
• Enhances C language with object-oriented programming features.
• Enables creation of reusable software components that model real-world items.
• Object-oriented design improves productivity in software development.

Overview of Python

• Created by Guido van Rossum and released in 1991.
• Gained popularity in education and scientific computing for several reasons:
  • Open-source, free, and widely available.
  • Backed by a large open-source community.
  • Easy to learn with readable code.
  • Extensive standard libraries that increase developer productivity.
  • Widely used in web development, AI, data science, and in finance.

C Programming Development Process

• C systems comprise a program development environment, the C language, and the C Standard Library.
• Execution of C programs involves six phases: edit, preprocess, compile, link, load, and execute.

Phase 1: Program Creation

• Involves editing a file using an editor.
• Common Linux editors: vi and emacs; IDEs like Eclipse and Visual Studio integrate editing tools.
• C program can be stored on a disk with the ‘-o’ flag indicating the output filename.

Phase 5: Loading

• Loader places the program in memory before execution, including additional components from shared libraries.

Phase 6: Executing

• The CPU executes the program one instruction at a time.
• On Linux: use ./a.out to execute; on Windows: simply type a.

Common Execution Issues

• Programs may not run correctly initially; errors can occur at any phase.
• Example: Division by zero causes the program to crash and display an error.

Standard Input, Output, and Error

• Most C programs handle data input/output through standard streams:
  • stdin for input (usually keyboard).
  • stdout for output (usually screen).
  • stderr for error messages, often routed to screen for immediate user feedback.

Objectives of C Programming

• Write simple programs and understand basic data types.
• Learn memory concepts and perform basic input/output operations.
• Execute arithmetic operations and recognize C keywords.

Structure of a Simple C Program

• Comments: Used for documentation, aid readability, and are ignored during compilation.
• #include: Pre-processor directive to include standard I/O operations.
• Main Function: Every C program starts in the main function; uses int for returning an integer.
• Curly Braces: Define the beginning and end of function bodies.

Output in C

• printf function used to display text.
• Example: printf("Welcome to C!\n");.

Linker and Executables

• The linker integrates standard library functions into the compiled code.
• Executable files can be run using the command ./a or ./programname.

Basic Data Types in C

• int: Integer, occupies 4 bytes.
• float: Floating-point numbers with 4 bytes.
• double: Double-precision floating point, occupies 8 bytes.
• char: Character, occupies 1 byte.

Variables and Memory in C

• Variables are defined with a name, associated with memory locations, and can be overwritten.
• Valid identifiers must consist of letters, digits, or underscores and cannot start with a digit; C is case-sensitive.

Basic Input/Output in C

• Use printf for output and scanf for input:
  • Example: scanf("%d", &b); retrieves an integer from keyboard input.

Arithmetic Operators in C

• Operators include addition (+), subtraction (-), multiplication (*), division (/), and modulo (%).
• Division by zero will result in an error.
• Parentheses can be used to group subexpressions.

Equality and Relational Operators

• Important for making comparisons in logic and control flow.

C Keywords

• Certain reserved words have specific meanings in C and shouldn't be used as identifiers in code.