Pointer in C programming language
In this tutorial, if to full use of c programming language , you have to must good understanding of pointer in c. You have to learn pointers because they are used everywhere in the C language. Once you understand full concept of pointer you can easily used in your C programming.
Following is a some topics that's we cover in this;-
What is a pointer in C
Declaration of pointer
How to use pointers
Null pointer in C
Array to pointer
1). What is a pointer in C
a pointer is a special types of variable that store the address of another variables.
a pointer is a similar to a variable but the different is that point store the address of the location in the memory and variable stored the value.
a pointer is a variable whose value is the address of another variable, means a direct address of the memory location.
you must declare a pointer before you can use it to store any variable address.
Ex.
int *ptr;
2). Declaration of pointer
Digital form of pointer variable declaration is
Data_Type *variable_name;
Here, type is the pointers best type, it must be a valid C data type and variable_name is the name of the pointer variable. The asterisk '*' you use to declare a pointer is the same as asterisk that you can use the for multiplication.
Some value declaration examples:-
int *ip; /*pointer to an integer*/
double *dp; /*pointer to an double */
float *cp; /* pointer to an float*/
3) how to use pointers?
This is is done by using unary operators * that returns the value of the variable located at the address specified by the operant.
Ex.
#include <stdio.h>
int main ()
{
int var = 50; /* actual variable declaration */
int *ip; /* pointer variable declaration */
ip = &var; /* store address of var in pointer variable*/
printf("Address of var variable: %x\n", &var );
/* address stored in pointer variable */
printf("Addr stored in ip variable: %x\n", ip );
/* access the value using the pointer */
printf("Value of *ip variable: %d\n", *ip );
return 0;
}
4) null pointer in C
A pointer that is assign null is called a null pointer.
It is always a good practice to assign a null value to a pointer variable in case you don't have any exact address to be assigned.
the null pointer is a constant with a value of zero defined in server standard libraries.
Following program for null pointer
#include <stdio.h>
int main ()
{
int *ptr = NULL;
printf("The value of ptr is : %x\n", ptr );
return 0;
}
Output:
The value of ptr is : 0
