Programming Theory Lecture Notes

Introduction

• Importance of programming theory for exams and practical programming.
• Difference between average and talented programmers often lies in understanding underlying concepts rather than just coding.

Data Types

• Definition: Classifying different types of data that determine operations and storage.
• Basic Primitive Data Types:
  • Integer: Whole numbers (e.g., 8, -35) without a decimal part.
  • Real (Float): Numbers with a decimal part (e.g., 2.0).
  • Boolean: Two possible values, true or false (1 or 0).
  • Character: A single letter, number, or symbol.
  • String: A set of characters (stored as an array).
• Casting: Changing a variable's type (e.g., converting an integer to a string by enclosing in quotes).

Programming Constructs

1. Sequence:
   • Code executed line by line in order.
   • Example: Print statements, variable assignments.
2. Selection:
   • Decision-making that determines which code to execute.
   • Uses conditional statements (if statements).
3. Iteration:
   • Repeating code until a condition is met.
   • Looping structures: while loops, for loops, do while loops.
   • Types of Loops:
     • Count Control Loops (Definite Loops): Known number of iterations (e.g., for loops).
     • Condition Control Loops (Indefinite Loops): Unknown number of iterations based on a condition (e.g., while loops, do while loops).

Variables

• Definition: References to memory locations containing single values.
• Identifiers: Names assigned to variables for easier reference.
• Variable characteristics:
  • Type and memory location usually fixed.
  • Values can change during execution.
• Declaration, Assignment, Initialization:
  • Declaration: Specify type.
  • Assignment: Store data.
  • Initialization: Assign value for the first time (best practice).

Constants

• Similar to variables but values cannot change during execution.
• Often written in capital letters to signify that they are constants.
• Benefits of using constants:
  1. Readability: Improves understanding of the code.
  2. Updateability: Easier to change values in one place rather than multiple instances.
  3. Compiler Optimization:
     • Constant folding: Evaluating expressions at compile time.
     • Constant propagation: Replacing constant names with literal values during compilation.

Conclusion

• Understanding these concepts is crucial for effective programming and exam preparation.