I am trying to understand whether references to array of unknown bound can be used as call parameter in functions in C . Below is the example that i have:
EXAMPLE 1
void func(int (&a)[])
{
}
int main()
{
cout << "Hello World" << endl;
int k[] = {1,2,3};
// k[0] = 3;
func(k);
return 0;
}
To my surprise this example 1 above works when compiled with GCC 10.1.0 and C 11 but doesn't work with GCC version lower that 10.x. I don't think that we can have references to arrays of unknown size in C . But then how does this code compile at the following link: successfully compiled
My second question is that can we do this for a function template? For example,
EXAMPLE 2
template<typename T1>
void foo(int (&x0)[])
{
}
Is example 2 valid C code in any version like C 17 etc. I saw usage of example 2 in a book where they have int (&x0)[]
as a function parameter of a template function.
CodePudding user response:
I don't think that we can have references to arrays of unknown size in C .
That used to be the case, although it was considered to be a language defect. It has been allowed since C 17.
Note that implicit conversion from array of known bound to array of unknown bound - which is what you do in main
of example 1 - wasn't allowed until C 20.
Is example 2 valid C code in any version like C 17
Yes; the template has no effect on whether you can have a reference to array of unknown bound.