Passing a bool as a param. C++

Question

what I am trying to do is an example below.

let's first define a bool.

bool cat = {false};

lets make a fake bool here.

bool setcat(bool booltoset)
{
 booltoset = true; 
 return booltoset;
}

now lets call it with cat.

printf("cat is %s", cat?"true":"false"); //set cat as false.

my question is; is it possible to actually pass a bool through an argument than set that bool?

Answer 1

You need to pass by reference, i.e.:

void setcat(bool& booltoset)
{
 booltoset = true; 
}

Answer 2

Any function argument is just a variable with scope identical to the function body. If it's an ordinary automatic variable, then changing it has not effect on the caller. This is sometimes useful: you can actually use the arguments, for example:

template<typename F>
void for_each(noexcept_it i, const noexcept_it end, const F &f) noexcept(noexcept(f))
{
   for(; i!=end; ++i) f(i);   // use i as iteration variable.
}

though the compiler will optimise such things anyway in most cases.