How does a pointer point to another pointer?
A pointer points to another pointer in the same way that a pointer points to a non-pointer object.
Start with a pointer to an object...
int a; // the object
int *pa = &a; // the pointer
pa; // is the value of the pointer
*pa; // is the value of the object
Now, create a pointer to a pointer to an object
int a; // the object
int *pa = &a; // the first pointer
int **paa = pa; // the second pointer
a; // is the value of the object
pa; // is the value of the first pointer
*pa; // is the value of the object using the first pointer
*paa; // is the value of the second pointer
**paa; // is the value of the object using the second pointer
And so on and so forth... Just don't forget to initialize each pointer along the way!
As the name suggests Pointer is used to point towards something ,here in this case it points to another variable and stored at a memory location. Pointer is a variable that stores address of another variable. Different Types of pointers are: 1)Dangling Pointers 2)NULL Pointers 3)This Pointer 4)Generic Pointer 5)Near Pointer 6)Far Pointer
When a variable is declared as being a pointer to type void it is known as a generic pointer. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. Hence the term Generic pointer.
void is type of pointer that usually means that you can make it point to any data type. When you make a pointer point to somewhere its data type should match with the place where you want it to point. When you dont know the data type where it will point to then you can declare a void pointer and make it point to the data type it want.
Pointer variables and function pointers are the two primary types, as well as a void pointer (unknown type). Pointer variables can point to any valid type, including primitive types and user-defined types, as well as other pointer variables. Function pointers can point to any function with the same signature as the function pointer itself. Void pointers can point anywhere.
A pointer can point to address of another pointer. consider the example int x=456, *p1, **p2;p1 = &x;p2 = &p1; Copyright Einstein College of EngineeringDepartment of Civil Engineering TOP printf("%d", *p1); will display value of x 456.printf("%d", *p2); will also display value of x 456. This is because p2 point p1, and p1 points x.Therefore p2 reads the value of x through pointer p1. Since one pointer is points towards anotherpointer it is called chain…
A NULL pointer is a pointer variable that stores the value zero. Although there is a memory address at offset 0, this value is reserved to indicate that the pointer is not pointing at any valid memory. A void pointer is a pointer variable that has no specific type. For instance, int * p; tells the compiler that p will point to a memory location that will be treated as if it were an int…
You cannot point at a class, you can only point at an instance of a class, which is simply another term for an object. The class is essentially the object's type; it define's the object's behaviour, but is not the object in and of itself. The class also defines a pointer's type, so we can point at instances of a class and access the the object it represents through indirection.
are usable. void pointer (generic pointer) : a special type of pointer which point to some data of no specific types. void *p; null pointer : a special type of pointer which point nowhere. it is usually used to check if a pointer is pointing to a null or free the pointer during deallocation of memory in dynamic memory allocation; it is define by using the predefine constant NULL int *p=NULL; wild pointer…
You get parallax errors with analogue meters if you don't align your eye so that it is perpendicular to the pointer. When this happens the pointer can appear to line up with the wrong mark on the scale. The further your point of view is away from the perpendicular, the greater the error. The potential for errors can be reduced by minimizing the gap between the pointer and the scale or better still fitting a…
That depends on which pole of the magnet it is moved close to. If it is brought close to the "South" pole of the magnet, the "North" pointer of the compass will be attracted to the magnet. If it is brought close to the "North" pole of the magnet, the "North" pointer of the compass will be repelled and will point AWAY from the magnet, while the "South" end of the compass pointer will point…