Pointer Arithmetic in C language

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Today we are going to discuss Pointer Arithmetic in C language.

Soo let’s start:)

Pointer in C is an address, which is a numeric value. Therefore, you can perform arithmetic operations on a pointer just as you can on a numeric value. There are four arithmetic operators that can be used on pointers: ++, –, +and -.

Let us study all these operators one by one in detail:-

1) Incrementing a Pointer:-
To understand pointer arithmetic, let us consider that ptr is an integer pointer which points to the address 1000. Assuming 32-bit integers, let us perform the following arithmetic operation on the pointer –
•Ptr++
• After the above operation ie:- increment , the ptr will point to the location 1004 because each time ptr is incremented, it will point to the next integer location which is 4 bytes next to the current location.
• This operation will move the pointer to the next memory location without impacting the actual value at the memory location.
• If ptr points to a character whose address is 1000, then the above operation will point to the location 1001 because the next character will be available at 1001.
• We prefer using a pointer in our program instead of an array because the variable pointer can be incremented, unlike the array name which cannot be incremented because it is a constant pointer.

Example:-
Use of increment operator to point to next memory location

Example 2:-
Display Array Elements using Pointer.

2)Decrementing a Pointer:-
•The same considerations apply to decrementing a pointer, which decreases its value by the number of bytes of its data type.
• Depending on the data type of the variable declared it decreases the value by that much byte.

•Example:-
Use of decrement operator to point to previous location.

Example 2:-
Display Reverse of Array using Pointer.

3) C Pointer Addition:-
We can add a value to the pointer variable. The formula of adding value to pointer is given below:

new_address= current_address + (number * size_of(data type))

Let us try to understand with the help of an example below:

Explanation:-
Here the statement p=p+5 will add 5*no of bytes required for storing integer variable. For eg:- if p contains 1000 and integer takes 2 bytes for storage then we will get. p=1000 + 5*2 = 1010

4) C Pointer Subtraction:-
Like pointer addition, we can subtract a value from the pointer variable. Subtracting any number from a pointer will give an address. The formula of subtracting value from the pointer variable is given below:

new_address= current_address – (number * size_of(data type))

Example on pointer subtraction:

Explanation:-
Here the statement p=p-3 will subtract 3*no of bytes required for storing
integer variable. For eg:- if p contains 1000 and integer takes 2 bytes for storage
then we will get. p=1000 – 3*2 =994

5) Subtraction of Two Pointers:-
•The subtraction of two pointers is possible only when they have the same data type.
• The result is generated by calculating the difference between the addresses of the two pointers.
• The subtraction of two pointers gives the increments between the two pointers.ie:-
It gives by how many bytes the pointer is increment.

Example:-

Here the difference printed will be in number of bytes.

Soo this is all about pointer arithmetic.

We will discuss some more related topics in upcoming articles.

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Keep reading,keep learning.

We will meet in the next article till then good bye,take care 🙂