Can Structures Have Pointers?


The book says, “A structure cannot contain an instance of itself. For example, a variable of type struct employee cannot be declared in the definition for struct employee . A pointer to struct employee, however, may be included.”

What is the structured variable?

structured variable A variable in a programming language that is a composite object, being made up of components that are either simple data items or are themselves structured objects; these components are identified by names.

Can a struct include itself in its definition?

struct rec { int i; struct rec r; }

A structure can not refer itself directly.

What is a void pointer?

A void pointer is a pointer that has no associated data type with it. A void pointer can hold address of any type and can be typcasted to any type.

What happens when a pointer to a structure is incremented?

When a pointer is incremented, it actually increments by the number equal to the size of the data type for which it is a pointer. For Example: If an integer pointer that stores address 1000 is incremented, then it will increment by 2(size of an int) and the new address it will points to 1002.

What is the use of pointer to structure?

Pointer to structure holds the add of the entire structure. It is used to create complex data structures such as linked lists, trees, graphs and so on. The members of the structure can be accessed using a special operator called as an arrow operator ( -> ).

What does a pointer do?

A pointer is a variable that stores a memory address. Pointers are used to store the addresses of other variables or memory items. Pointers are very useful for another type of parameter passing, usually referred to as Pass By Address.

How can a function pointer be declared?

A pointer to a function points to the address of the executable code of the function. You can use pointers to call functions and to pass functions as arguments to other functions. … You can use a trailing return type in the declaration or definition of a pointer to a function.

What is a generic 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.

Can pointer be incremented?

A pointer can be incremented by value or by address based on the pointer data type. For example, an integer pointer can increment memory address by 4, since the integer takes up 4 bytes.

Can a pointer be subtracted from another pointer?

Two pointers can also be subtracted from each other if the following conditions are satisfied: Both pointers will point to elements of same array; or one past the last element of same array. The result of the subtraction must be representable in ptrdiff_t data type, which is defined in stddef.

What is pointer with example?

A pointer is a variable that stores the address of another variable. … For example, an integer variable holds (or you can say stores) an integer value, however an integer pointer holds the address of a integer variable.


What is null and void pointer?

A null pointer is basically a null value assigned to a pointer of any data type whereas a void pointer is a data type which remains void as long as an address of a data type is not assigned to it. … Null pointer does not contain a reference of any variable/value.

What can’t you do on a void pointer?

Because the void pointer is used to cast the variables only, So pointer arithmetic can’t be done in a void pointer.

Where is void pointer used?

void pointers should be used any time the contents of a block of data is not important. For example when copying data the contents of a memory area is copied but the format of the data is not important.

What happens if we subtract two pointers?

When two pointers are subtracted, both shall point to elements of the same array object, or one past the last element of the array object; the result is the difference of the subscripts of the two array elements. Note that when allowed, the result is the subscripts difference.

Can two pointers be compared?

When two pointers are compared, the result depends on the relative locations in the address space of the objects pointed to. If two pointers to object types both point to the same object, or both point one past the last element of the same array object, they compare equal.

WHAT IS NULL pointer in C?

A null pointer is a pointer which points nothing. Some uses of the null pointer are: a) To initialize a pointer variable when that pointer variable isn’t assigned any valid memory address yet. b) To pass a null pointer to a function argument when we don’t want to pass any valid memory address.

What does * p ++ do in C?

In C programming language, *p represents the value stored in a pointer. ++ is increment operator used in prefix and postfix expressions. * is dereference operator. Precedence of prefix ++ and * is same and both are right to left associative.

Why can’t we increment an array like a pointer?

It’s because array is treated as a constant pointer in the function it is declared. There is a reason for it. Array variable is supposed to point to the first element of the array or first memory instance of the block of the contiguous memory locations in which it is stored.

What happens if you add one to a pointer?

A pointer addition means passing to some next pointed element. So the address is incremented by the sizeof the pointed element. The address of the pointer will be incremented by sizeof(T) where T is the type pointed to. So for an int , the pointer will be incremented by sizeof(int) .

Can generic pointer be dereferenced?

void pointer in C / C++

In C++, we must explicitly typecast return value of malloc to (int *). 2) void pointers in C are used to implement generic functions in C. For example compare function which is used in qsort(). … 1) void pointers cannot be dereferenced.

What is size of void pointer?

The size of void pointer varies system to system. If the system is 16-bit, size of void pointer is 2 bytes. If the system is 32-bit, size of void pointer is 4 bytes. If the system is 64-bit, size of void pointer is 8 bytes.