Back from the Future

Test your C++ programming skills by solving the given puzzle about data races and the importance of thread-safe operations.

We'll cover the following

Puzzle code

Carefully read the code given below:

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#include <future>
#include <iostream>
int main()
{
    char counter = 0;
    auto future1 = std::async(std::launch::async, [&]()
    {
        counter++;
    });
    auto future2 = std::async(std::launch::async, [&]()
    {
        return counter;
    });
    future1.wait();
    
    // Cast to int to print it as a numerical value rather than a character
    std::cout << (int)future2.get();
}

Your task: Guess the output

Try to guess the output of the above code. Attempt the following quiz to assess your understanding.

Q

What is the expected output of the above code?

A)

0

B)

1

C)

Undefined behavior

D)

Runtime error

Let’s discuss this code and output together in the next lesson.

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