Now that we know how to ask questions (True/False), we must act based on the answer. This is where conditional statements come in: If, Elif (Else if), and Else.

Let’s use the Rook as an example. The Rook moves only horizontally or vertically. To move a rook from a starting position (r1, c1) to a destination (r2, c2), one of these two conditions must be true:

• The row does not change (r1 = r2) --> Horizontal Movement.
• The column does not change (c1 = c2) --> Vertical Movement.

The if / else Structure

# Starting coordinates (row, column)
r1, c1 = 4, 4  # Example: Square e5 (indices 4, 4)
# Destination coordinates
r2, c2 = 4, 7  # Example: Square h5 (indices 4, 7)
# Geometric validation logic
if r1 == r2:
    print("Valid Horizontal move for the Rook")
elif c1 == c2:
    print("Valid Vertical move for the Rook")
else:
    print("Error: The Rook cannot move diagonally or in an L-shape")

Code Analysis:

• if: The computer checks the first condition. If it is True, it prints the message and skips the rest.
• elif (else if): If the first condition was False, it checks this one.
• else: If none of the above were True, it executes this "default" block (illegal move).