C Pointers

C Pointers

Pointers

Creating Pointers

A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location. Like any variable or constant

Pointers in C are easy and fun to learn. Some C programming tasks are performed more easily with pointers, and other tasks, such as dynamic memory allocation, cannot be performed without using pointers. So it becomes necessary to learn pointers to become a perfect C programmer.

Some of the valid pointer declarations -

Example - create pointer

int A = 20;/* actual variable declaration */ int *ip;/* pointer variable declaration */ ip = &A;/*store address of var in pointer variable*/ printf("Address of A variable: %x", &A); /* address stored in pointer variable */ printf("Address stored in ip variable: %x", ip); /* access the value using the pointer */ printf("Value of *ip variable: %d", *ip);

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NULL Pointers

It is always a good practice to assign a NULL value to a pointer variable in case you do not have an exact address to be assigned. This is done at the time of variable declaration. A pointer that is assigned NULL is called a null pointer.

Example - null pointer

int *ptr= NULL; printf("The value of pointer is %u",ptr);//initialize the pointer as null return 0;

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Dereference

The pointer variable to get the memory address of a variable used together with the & reference operator. The value of the variable the pointer points to, by using the * operator is the dereference operator.

Example - dereference

int Num = 1; int* ptr = &Num; // Pointer declaration // memory address of Num with the pointer printf("%p", ptr); // Dereference: Output the value of Num with the pointer printf("%d", *ptr);

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