What do you mean by function to pointer?

Answer 1

Answer

• I take it you are using some version of c,c++,visualC etc etc. One thing that is standard is pointers. A pointer is the address of a memory space that holds information in that specific space. By referencing the pointer in your code, you can print out that specific bit of information that the poiner is actually pointing to. Hope this helps

Answer 2

An array of pointers is exactly what is says on the tin - an array which contains pointers to memory addresses.

If you were to create an array of ten integers like this:

int array[10];

This would create an array which you could directly access from the stack (memory allocated to the program by the Operating System).

However, if you wanted to create an array of pointers to integers, allowing for a more efficient use of memory, you could do this:

int *array = new int[10];

This dynamically allocates an array of 10 pointers to integers.

Comment:

This example is hardly an efficient use of memory. Not only are you declaring 10 integers, you are declaring a pointer, which uses slightly more memory than would otherwise be required by the first example. An array of pointers is more useful when the memory they point to is non-contiguous and the number of elements is dynamic rather than static. Even dynamic multi-dimensional arrays can be allocated in contiguous space and simple pointer arithmetic can be used to access any element, thus only one pointer is required for the entire array rather than separate arrays of pointers and pointer-to-pointer arrays for each dimension. While pointer arrays can often improve performance, it is always at the expense of memory consumption.

Answer 3

1. #include
2. using namespace std;
3. main()
4. {
5. int * add(int,int);
6. int *ptr;
7. int x,y;
8. cin>>x>>y;
9. ptr=add(x,y);//address of the result variable is assigned to ptr
10. cout<<"result is"<<*ptr;
11. }
12. int *add(int a,int b)
13. {
14. int c=a+b;
15. return(&c);
16. }
17. #include
18. using namespace std;
19. main()
20. {
21. int add(int,int);
22. int (*ptr)(int,int);//declaring function pointer
23. int x,y,result;
24. cin>>x>>y;
25. ptr=add //address of the function is assinged to ptr
26. result=(*ptr)(x,y);
27. }

Answer 4

You point at the array the same way you would with an array of any pointer type, by using an additional level of indirection than is employed by the pointers in the array itself. In this case, the array contains pointer-to-function data types (with one level of indirection), thus you must use a pointer-to-pointer-to-function data type (with two levels of indirection) in order to point at the array itself.

Had the array contained pointer-to-pointer-to-function data types (where each pointer points to a separate array of pointer-to-function data types), then you'd use three levels of indirection, and so on.

You increase the level of indirection by placing an additional asterisk before the pointer's name when you declare the pointer. That is, one asterisk per level.

Answer 5

A pointer is a variable that stores a memory address. If the address is non-null (non-zero) that address can be dereferenced to access the value stored at that address.

Pointers are necessary when referring to objects allocated on the heap because objects on the heap have no name, they can only be accessed via their memory address (their actual identity). Resource handles and smart pointer objects allow access to heap-based objects in languages that have no concept of a "raw" pointer.

Pointers are also useful in that the same variable can be used to refer to different objects simply by changing the address stored in the pointer. This makes it possible to pass by reference in languages that only support pass by value semantics. Pointers are copied, but the since the value of a pointer is an address, it is the same as passing the address, by reference.

Answer 6

typedef void (*myfunptr)(void);

extern void fun1 (void), fun2 (void), fun3 (void);

myfunptr ptrs[] = {fun1, fun3, fun3};

ptrs[0]();
ptrs[1]();
...

Answer 7

Nothing. You might have meant pointer-to-function.

Answer 8

Yes. A function can return a pointer...

const char* GetHelloString() { return "Hello!"; }

... returns a pointer to the string "Hello!".