Lecture on If-Else Statements

Introduction

• Review of if statements:
  • If a condition is true, execute some code.
  • Example: "if the front is clear, then move."

Introduction to If-Else Statements

• Purpose:
  • Handle situations where actions depend on conditions.
  • Execute different code blocks based on the truth value of a condition.
• Structure:
  • If the condition is true, execute code block A.
  • Else, execute code block B.
• Example: "if the front is clear, move; else, turn left."

Benefits of If-Else Statements

• Allow solving more general problems by handling different world scenarios.
• Transition from specific solutions to flexible code.

Example 1

• Original approach:
  • Command: Move twice.
  • Issue: Carol crashes into a wall.
• Using If statements:
  • Condition: If front is clear, then move.
  • Result: Avoids crashing by checking condition.
• Using If-Else statements:
  • Condition: If front is clear, move; Else, turn left.
  • Result: Turns left only when the front is not clear.

Example 2

• Goal: Put one ball in each spot.
• Initial approach:
  • Command sequence: Put ball, move, move, put ball.
  • Problem: Works for one world but not another.
• Solution:
  • Define a function check_ball:
    • Check if no balls are present, then put a ball.
  • Apply function and repeat move steps.
  • Adapted the code for multiple worlds by making it more generic.

Conclusion

• Writing generic code with if-else statements enables solving problems in different scenarios.
• Encouragement to explore and practice with if-else statements.