What is Pointer? this is a question who trouble many of us, so i decide to write on it, hope it helps you 🙂
When we define a variable in c or whatever language, the compiler will find unused/vacant location in memory and allocate that to variable, to use. As we know area of memory consist of lot of cells and each cell is identified by a unique number, that unique number is known as memory address or address. Size of each memory cell is 1 byte.
Like any other data type as integer (int), character (char), floating point numbers (float), etc. Address also requires a data type to store, that is the reason pointer come in existence.
Declaration of pointer variable:
<Data Type> * <Variable name>; Example : int * p; // here p is pointer to integer or integer pointer similarly char * p1; // here p1 is pointer to character or character pointer
Finding address of a variable:
The address of variable can be obtained by using & (ampersand) operator, by placing the & operator in front of the variable’s name. when & operator is used as unary operator with a pointer variable, then it is known as address-of operator.
Example : int m; int *p; then p = &m;
here from the above statement, expression p = &m storing the address of m variable into the point variable p.
Important Points :
- The Address-of operator can be only used with variables and array elements.
- The data type of data variable and address variable must be same. let suppose p = &m here data types of pointer variable p and data variable m must be similar.
Getting Content of a variable using pointer :
To get content of a variable which is pointed by a pointer, uses the * (asterisk) operator. if * symbol used as unary operator with the pointer variable then it gives value of that variable. Then * operator is known as de-referencing operator.
example :
int x = 1, y;
int *p = &x; // intializing pointer variale p with address of x
y = *p; //getting content of that address to which it is pointing i.e. x
printf("%d", &y); // here it gives output as 1.
Types of pointer:
- Null Pointer : A pointer i.e. assigned null is null pointer. e.g. int *p = Null;
- Pointer Arithmetic : Pointer arithmetic means, we can perform arithmetic operation on the pointer. There are only ++, –, +, – operations are possible to perform of pointer.
- Pointers and Array : Pointer that points to the beginning of an array can access that array by using either pointer arithmetic or array style indexing.
If You need help on any specific topic. Please let me know. I will try my best to solve your problem. Thanks, 🙂