13. Selection

Selection is one of the three basic control structures:

Sequence (steps in order)
Selection (branching using if … elif … else)
Iteration (repetition or looping using while or for)

Selection provides choice or branches in the code.

13.1. If, elif, else

if is used with a condition that results in True or False.
When the condition is True, the code indented below the if statement is executed.
Alternatives can be provided using elif with a condition.
If all conditions are False, else: can be used to execute other code.
Note that there must be a colon, :, at the end of each if, elif and else statement.

In the code below, scoreA is compared to scoreB.

scoreA = 88
scoreB = 85
if scoreA > scoreB:
    print("A won")
elif scoreB > scoreA:
    print("B won")
else:
    print("A drew with B")

Tasks

Add the variables teamA and teamB and set team names for them. Modify the code to print the team name instead of ‘A’ or ‘B’. Hint: To join text use a plus symbol. e.g (myteam + “ my text”)

13.2. Nested if

Nesting includes other if statements have within if statements.

Both the if and the elif have a nested if and else that are used when their condition is True.

scoreA = 120
scoreB = 55
if scoreA > scoreB:
    if scoreA - scoreB > 60:
        print("A won easily")
    else:
        print("A won")
elif scoreB > scoreA:
    if scoreB - scoreA > 60:
        print("B won easily")
    else:
        print("B won")
else:
    print("A drew with B")

Tasks

Add the variables teamA and teamB and set team names for them. Modify the code to print the team name instead of ‘A’ or ‘B’. Hint: To join text use a plus symbol. e.g (myteam + “ my text”)
Modify the code to print the winning margins. Use str(number) to convert numbers to text for joining with other text. Add the variables teamA_win_by and teamB_win_by. Calculate those variables using scoreA and scoreB. e.g teamA_win_by = scoreA - scoreB. Replace “A won easily” with code to output “A won easily by 65”. Do similar replacements for the other printed text.