Choosing which block of code to execute based on whether a condition is true or false. Selection allows programs to make decisions, following one path when a condition holds and a different path otherwise, using constructs like if, else-if, and else.
If this is true, do that path. If it is false, take a different path instead.
Showing a random 20 of 50 problems.
Example 1
medium
Trace: x=10,y=20; if x>5 and y>25: 'A' else 'B'. What prints?
Example 2
easy
In most programming languages, which symbol tests equality (not assignment)?
Example 3
easy
Trace: g=85; if g≥90: 'A' elif g≥80: 'B' else 'C'. What prints?
Example 4
medium
Write pseudocode using IF-ELIF-ELSE to assign a grade: 90+ = A, 80–89 = B, 70–79 = C, below 70 = F.
Example 5
easy
`n = 5`; `if n % 2 == 0: print('even') else: print('odd')`. What prints?
Example 6
medium
`x = 100`; `if x > 10: print('A') elif x > 50: print('B') elif x > 90: print('C')`. What prints, and why is B/C dead?
Example 7
medium
A chain uses 'if x>0: A elif x>10: B'. For x=15, which prints, and what design flaw exists?
Example 8
hard
A function returns 'tween' if 10 <= age <= 12, 'teen' if 13 <= age <= 19, else 'other'. What does it return for age = 13?
Example 9
easy
In code, what symbol compares two values for equality (not assignment)?
Example 10
medium
Trace: temp=30; if temp>25: ac='on'; else: ac='off'. What is ac?
Example 11
medium
Trace: score=72; if score≥60: pass=true; if score≥90: honors=true. What are pass and honors?
Example 12
challenge
Convert this to a single condition: 'if x>0: if y>0: print P'. Write the equivalent one-line condition.
Example 13
challenge
A grading chain checks ≥90 then ≥80 then ≥70. A bug orders them ≥70 first. For score 95, what grade results and why is it wrong?
Example 14
easy
Is 'if temp = 100' a correct condition in a language that distinguishes = and ==? Yes or no.
Example 15
hard
Bug: a chain checks `if score >= 70 elif score >= 80 elif score >= 90`. For score=95 what grade results, and why is it wrong?
Example 16
medium
Identify whether this is selection or iteration: 'while x < 10: x = x + 1'. Answer with one word.
Example 17
medium
`x = 10, y = 5`; `if x > 0 and y > 0: print('Q1')`. Does Q1 print?
Example 18
easy
Which clause in an `if`/`elif`/`else` chain handles every case not matched by an earlier condition?
Example 19
hard
`x = 4`; `if x % 2 == 0 and x > 0: r='ep' elif x % 2 == 0: r='en' else: r='o'`. What is r?
Example 20
easy
Which control structure lets a program take a different path when a condition is false?