ctf Lesson 3 8 min read

CTF: If/Else Decisions

4 challenges — Week 4

If/Else Decisions Challenges

4 challenges Week 4 Week 4 (C Control Flow, Functions, and Writing Real Programs)

Exercises covering conditional logic including assertions, boolean/logical expressions, if/else/else-if chains, and debugging conditional code in C.

Difficulty Breakdown

Level Count
Beginner 3
Intermediate 1

Challenges

1. Assertions1

Difficulty: Intermediate Time: ~15 min Type: assertion table

For each of the five points labeled by comments, identify each of the assertions in the table below as either being always true, never true, or sometimes true / sometimes false.

Concepts: program state reasoning at specific execution points, while loop invariant analysis, conditional (if) statement path analysis, variable initialization and mutation tracking, understanding always/never/sometimes assertion logic

Practice on CodeStepByStep

2. Earlier Date

Difficulty: Beginner Time: ~10 min Type: function

Write a function earlier_date that takes as parameters two month/day combinations and that prints out the earlier date. The function will take four integers as parameters that represent the two month/day combinations (month1, day1, month2, day2). Compare months first, then days to break ties. Print the earlier date in month/day format.

Concepts: compound boolean expressions (&&,   ), if/else decision making, comparing multi-field data (month then day), function definition with parameters, printf formatting with %d

Practice on CodeStepByStep

3. Logical Expressions

Difficulty: Beginner Time: ~8 min Type: expression evaluation

Trace the evaluation of the following expressions, and give their resulting values. Write true if the expression would have a true result and false otherwise.

int x = 42; int y = 17; int z = 25;

Concepts: logical AND (&&) and OR (   ) operators, logical NOT (!) operator, operator precedence with logical operators, modulo operator in boolean context, compound boolean expression evaluation

Practice on CodeStepByStep

4. Percentage Grade

Difficulty: Beginner Time: ~8 min Type: bare code
What’s wrong with the following code? Modify it to produce the intended output. Make sure to properly utilize if/else/if statements to avoid redundancy and avoid unnecessary tests. Do not use && or   in your solution.

Concepts: if vs else-if chains (mutually exclusive conditions), debugging existing code, understanding why separate if statements cause multiple matches, proper use of else for default/catch-all case, scanf and printf for interactive I/O

Practice on CodeStepByStep