I'm learning C. I know what the first line is doing; it's making a pointer to a function with no arguments and it returns an int. But wtf is the second doing?
My guess is that it is casting an int into a function? But what does it mean to turn an int into a function? Also, why does it cause an error when I try to call the function: 'function()'?
int (*function) ();
function = (int (*) ()) (1000);
Overall, the code is nonsense. Where did you get it from?
it's making a pointer to a function with no arguments
Rather, it is making a pointer to a function with obsolete style parameter list.
But wtf is the second doing?
It assigns the function pointer to point at address 1000 (decimal), my means of a cast from int to the function pointer type.
why does it cause an error when I try to call the function: 'function()'?
Likely because there is no such function allocated at address 1000. You might not even have access to that area etc.
learning function pointer is pain in ass. simple example maybe help for better understand.
suppose you want point to this function:
int sum (int a , int b) {
return a+b;
}
so you need define a pointer with same type:
int *pointerToSum (int, int);
and simply assign it to function:
pointerToSum = ∑
if you want use it:
(*pointerToSum)(3, 5); //8
you can use function-pointer tag to find out more complex answers.
your question delete by people because there is duplicate question asked before.
I implement function-pointer for myself and it's a little complex and you can see in : exercise of function pointer
I wish you the best.
int (*function)(void);