CODEWITHSUNDEEP
c++
BendedWills
BendedWills

Reputation: 99

Is there a better way to invert the value of a boolean on a loop?

I have this loop here that alternates a boolean.

Here is what I mean:

bool switch = false;

while(true) {
    switch = !switch;
    std::cout << switch << std::endl;
}

Every time this code loops, the boolean named switch will alternate between true and false.

Something like:

bool switch = false;

while(true) {
    std::cout << !switch << std::endl;
}

There is really nothing wrong with this but I would like a one-line solution.

Of course, that doesn't work but something similar to that.

Upvotes: 2

Views: 1475

Answers (5)

Bob__
Bob__

Reputation: 12749

If you are in the mood for overcomplicating things, here is the "enterprise edition":

#include <iostream>

class SwitchingBool
{
    bool state_{};
public:
    operator bool()   const noexcept { return state_; }
    bool operator()()       noexcept { return (state_ = !state_); }
    // Or use a named accessor or a named mutator or invert the bodies or ...
};

int main()
{
    SwitchingBool blinker;
    
    std::cout << std::boolalpha;
    for (int i{}; i < 10; ++i)
    {
        std::cout << "From " << blinker << " to " << blinker() << '\n';
    }
}

Upvotes: 0

cigien
cigien

Reputation: 60208

From c++20, you can write:

for (auto b : std::views::iota(1)) 
{
    std::cout << b % 2 << std::endl;
}

Here's a demo.

Upvotes: 0

Jeremy Friesner
Jeremy Friesner

Reputation: 73051

I think the way you have it is fine, but another way to do it would be like this:

unsigned int count = 0;

while(true) {
   std::cout << ((++count%2) != 0) << std::endl;
}

Upvotes: 1

3CxEZiVlQ
3CxEZiVlQ

Reputation: 38341

std::cout << (switch = !switch) << std::endl;

Or

std::cout << !switch << std::endl << switch << std::endl;

Upvotes: 3

paxdiablo
paxdiablo

Reputation: 881193

If all you want to do is change switch and output it in one line of code, you can do:

std::cout << (switch = !switch) << std::endl;

But that's almost certainly not going to do anything other than reduce your line count by one, a dubious achievement at best. It'll most likely end up as the same underlying machine code.

Upvotes: 2

Related Questions