Control Flow - Quiz

Which statement best describes an if-else statement in C++?

When is a switch statement generally preferred over multiple if-else statements?

What happens if the condition of a while loop is initially false?

In a for loop, when is the increment expression executed?

Which loop guarantees its body executes at least once?

Which range-based for loop correctly modifies all elements of a std::vector<int> v?

What is the main risk of forgetting a break statement in a switch case?

Which for loop header correctly iterates over indices 0 to n-1 for a std::vector<int> v?

Which construct is best for repeatedly asking the user for a menu choice until they choose 'Exit'?

In modern C++, which is usually the safest way to iterate over all elements of a std::vector<std::string> v for read-only access?

Complete the if statement to check if a std::unique_ptr<int> p is not null before dereferencing.

Complete the for loop header to iterate 10 times using i from 0 to 9.

Use a range-based for loop to print all values in a std::vector<int> v.

What is the output of this code?

1#include <iostream>
2
3int main() {
4    int x = 3;
5    if (x > 5)
6        std::cout << "A";
7    else if (x > 2)
8        std::cout << "B";
9    else
10        std::cout << "C";
11    return 0;
12}

What does this switch statement print?

1#include <iostream>
2
3int main() {
4    int grade = 85;
5    switch (grade / 10) {
6        case 10:
7        case 9:
8            std::cout << "A";
9            break;
10        case 8:
11            std::cout << "B";
12            break;
13        case 7:
14            std::cout << "C";
15            break;
16        default:
17            std::cout << "D";
18    }
19    return 0;
20}

What is the output of this for loop?

1#include <iostream>
2
3int main() {
4    for (int i = 0; i < 3; ++i) {
5        std::cout << i << " ";
6    }
7    return 0;
8}

What does this while loop print?

1#include <iostream>
2
3int main() {
4    int n = 5;
5    while (n > 0) {
6        std::cout << n << " ";
7        --n;
8    }
9    return 0;
10}

What is the output of this range-based for loop?

1#include <iostream>
2#include <vector>
3
4int main() {
5    std::vector<int> v{1, 2, 3};
6    for (auto& x : v) {
7        x *= 2;
8    }
9    for (const auto& x : v) {
10        std::cout << x << " ";
11    }
12    return 0;
13}

Find the bug in this input loop that should stop when the user enters 0.

Click on the line(s) that contain the bug.

#include <iostream>

int main() {

    int value;

    while (value != 0) {

        std::cin >> value;

        std::cout << "You entered: " << value << std::endl;

    }

    return 0;

}

Find the bug related to loop control and memory management.

Click on the line(s) that contain the bug.

#include <iostream>

void fillArray(int n) {

    int* data = new int[n];

    int i = 0;

    while (i <= n) {

        data[i] = i;

        ++i;

    }

    delete[] data;

}

int main() {

    fillArray(5);

    return 0;

}

Click the line that causes a potential infinite loop when input fails.

Click on the line to select.

#include <iostream>

#include <limits>

int main() {

    int number;

    std::cout << "Enter a positive number: ";

    while (number <= 0) {

        std::cin >> number;

        if (std::cin.fail()) {

            std::cout << "Invalid input\n";

        }

    }

    std::cout << "You entered: " << number << std::endl;

    return 0;

}

Click the line where the control-flow decision for exit is made in this menu loop.

Click on the line to select.

#include <iostream>

int main() {

    int choice = 0;

    do {

        std::cout << "1. Start\n2. Settings\n3. Exit\n";

        std::cin >> choice;

        switch (choice) {

            case 1:

                std::cout << "Starting...\n";

                break;

            case 2:

                std::cout << "Opening settings...\n";

                break;

            case 3:

                std::cout << "Exiting...\n";

                break;

            default:

                std::cout << "Invalid choice\n";

        }

    } while (choice != 3);

    return 0;

}

Complete the if-else chain to categorize an HTTP status code.

Complete the for loop that sums elements of a std::vector<int> v.

Complete the while loop that reads integers until -1 is entered.

Complete the range-based for loop to print all characters in a std::string s.

Match the control-flow construct with its typical use case.

Click an item on the left, then click its match on the right. Click a matched item to unmatch.

Match the C++ feature with the most idiomatic loop structure.

Click an item on the left, then click its match on the right. Click a matched item to unmatch.

Order the steps for processing items from a std::vector<int> using a range-based for loop.

Drag and drop to reorder, or use the arrows.

Order the steps to implement a robust input-validation loop using while.

Drag and drop to reorder, or use the arrows.