Pointers In C

  • Pointer are the variables which stores the address of another variable.
  • It can only store address of variable only when their data types are same.
  • For example:int type of pointer can only store address of integer type of variable.
  • Float type of pointer can only store address of float type of variable And so on.
  • let's declare some pointer variables.

Syntax:declaring pointer
datatype  *pointer_variable_name
  • We use '*' operator to declare pointer variable

    • Declaring : pointer variables
    #include<stdio.h>
void main()
{
int *i_p; //int type of pointer
       //it can store address of integer variable.

float *f_p; //float type of variable 
            //it can store address of float variable.


char *c_p //char type of pointer
         //it can store address of character variable. 
}

    let's use above declare pointers.

    Assigning: Address of int varaible to pointer variable
    #include<stdio.h>
void main()
{
int i_var = 10; //integer variable.

int *i_p;  //int type of pointer
            //it can store address of integer variable.

       
i_p  = &i_var; //assigning address of i_var variable
                  //to a pointer variable i_p.

}

    Lets understand visually.





    Assigning: Address of float varaible to pointer variable
    #include<stdio.h>
void main()
{
float f_var = 1.2; //float variable.

float *f_p;  //float type of pointer
            //it can store address of float variable.

       
f_p  = &f_var; //assigning address of f_var variable
                  //to a pointer variable f_p.

}

    Lets understand visually.



    Assigning: Address of char variable to pointer variable
    #include<stdio.h>
void main()
{
char c_var = 'A'; //char variable.

char *c_p;  //character type of pointer
            //it can store address of char variable.

       
c_p  = &c_var; //assigning address of c_var variable
                  //to a pointer variable c_p.

}

    Lets understand visually.



    You can know the address of variable by Using & operator
    let's use it.

    Printing address
    #include<stdio.h>
void main()
{
int i_var;//integer variable.

printf("%u",&i_var);  //printing address
}

    Output:
    655489.
    • You can use %d specifier instead of %u but using %u specifier is good for printing Addresses of variables.

    Accessing variables

    • From pointer variable we can access the variable whose address is stored by pointer.
    • It can done by using * Operator.

      • Syntax : Accessing variables from pointer variable
      *pointer_name

    Lets Access the variable:
    #include<stdio.h>
void main()
{
int i_var = 10;
int acc_var;

int *i_p; //int type of pointer
        //it can store address of integer variable.

i_p  = &i_var;//assigning address of i_var variable
             //to a pointer variable i_p.
             
acc_var = *i_p;//assigning accessed value from pointer
               //to variable acc_var.

    let's print the accessed value:
    printf("variable stored by pointer was %d", acc_var);

    Output:
    variable stored by pointer was 10.

    Let's see another example:
    #include<stdio.h>
void main()
{
float f_var = 1.2;
float acc_var;

float *f_p; //float type of pointer
        //it can store address of float variable.

f_p  = &f_var;//assigning address of f_var variable
             //to a pointer variable f_p.
             
acc_var = *f_p;//assigning accessed value from pointer
               //to variable acc_var.

    let's print the accessed value:
    printf("variable stored by pointer was %f", acc_var);

    Output:
    variable stored by pointer was 1.2.

    Let's Access character variable:
    #include<stdio.h>
void main()
{
char c_var = 'A';
char acc_var;

char *c_p; //float type of pointer
        //it can store address of char type variable.

c_p  = &c_var;//assigning address of c_var variable
             //to a pointer variable c_p.
             
acc_var = *c_p;//assigning accessed value from pointer
               //to variable acc_var.

    let's print the accessed value:
    printf("variable stored by pointer was %c", acc_var);

    Output:
    variable stored by pointer was A.
    • This how pointer works.
    • This is a basics of pointers, So keep a good command on your basic , so you can easily understand advance concepts of Pointers



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