Programming Logic and Design: For Loop

Introduction

• For Loop: A definite loop that executes a specific number of times.
• Example: The loop will execute exactly 4 times (0, 1, 2, 3).

Key Actions in For Loop

1. Initialization: Setting the count to zero.
2. Evaluation: Checking if the count is less than or equal to 3.
3. Alteration: Incrementing count by 1.

Steps in Execution

• Initial value count = 0.
• Evaluate if 0 <= 3 (true) → Output "hello" → Increment to count = 1.
• Evaluate if 1 <= 3 (true) → Output "hello" → Increment to count = 2.
• Evaluate if 2 <= 3 (true) → Output "hello" → Increment to count = 3.
• Evaluate if 3 <= 3 (true) → Output "hello" → Increment to count = 4.
• Evaluate if 4 <= 3 (false) → Exit loop.

Comparison: For Loop vs. While Loop

• For Loop: Fewer lines of code (3 lines).
• While Loop: More lines of code (5 lines).
  • Initialization before entering the loop.
  • Evaluation condition.
  • Output statement.
  • Increment count.
  • Re-evaluate condition and repeat steps.

Efficiency

• For Loop: Loop control variable is handled automatically, leading to fewer lines of code and increased processing time.

Step Value

• Default: Step value is 1.
• Can be positive or negative.
• Programmers can specify any step value.
• Example: Increment by 2 → 2, 4, 6, etc.

Structure of For Loop

• Keywords: for and endfor.
• Variables:
  • Loop control variable (e.g., count).
  • Initial value.
  • Final value (end of iteration).
  • Step value (amount changed per loop).

Types of Loops

• Pre-test Loop: Control variable tested before each iteration (for loops and while loops).
• Post-test Loop: Control variable tested after each iteration (do-while and do-until loops).

Next Topic

• Will discuss common loop applications in the next video.