Pointers in C programming Language

Pointers in C Programming Language

In this tutorial, we will discuss the concept of Pointers in C Programming Language

Knowledge area

• What is the pointer in C
• Declaration & initiation of pointer
• find variable address & pointer
• Advantages and disadvantages of pointer

pointer

• The pointer is one of the features of C language like C++
• The pointer is a very fundamental and important concept program in C Language.
• The pointer is one of the variables is basically same as other variables in C. Which can store a piece of data
• The normal variable which stores a value such as an int, a double. a char.
• A pointer store a memory address is similar to an array but array is statically pointer is dynamical. dynamically means we can increase or decreased memory allocation to my need.
• So the pointer is a special type of variable that contains just the address of another variable. it is called pointer

what is a memory unit

As we know, a memory unit is a collection of storage  cells which can  store information
Each memory cell is given an identification by address(some times may be number), it’s called address
if memory can store n  information it addresses ranges from 0 to n-1.

Declaring and initialising pointers

All pointers variable must be declared before it is used in the program like other variables. The general form is,

Syntex

var – it is a variable on your program in C
&var – it is an address of your variable in the memory location
*var – it is a pointer of your memory location

data type* var;      // Dicare a pointer variable called var as the pointer of type
data type *var;
data type * var;

– data type means such as int, float double etc 

* (sign) – to identify the variable as a pointer

*ptr – this is a pointer variable
var- this is a normal variable

Example :
                  int *a;  // Decare a pointer variable called as  pointing to an int
                                // it contain an address holds an int value
                 
                                                 or

                 char* a;  // Dicare a pointer variable called an as  pointing to a char
                                   // it contains an address holds a char value

                                                   or 

                   double * a;  // Dicare a pointer variable called a as  pointer  a double
                                        // it contains an address holds a double value
Program 1

How to find the  variable address at the memory location

#include <stdio.h>
#include <stdlib.h>

int main()
{
  int a=0;                               //assign int type a, initialized value 0
    int b=25;                          //assign int type b,and initialized value 25
    float c=3.45;                     //assign float type c and initialized 3.45
    printf(“value of a:%dn”,a);  //disply value of a
    printf(“value of b:%dn”,b);  //disply value of b 
    printf(“value of c:%fn”,c);   //disply value of c
    printf(“……………n”);
    printf(“address of a:%un”,&a);  //disply address of a in memory location
    printf(“address of b:%un”,&b);  //disply address of b in memory location
    printf(“address of c:%un”,&c);   //disply address of b in memory location
    return 0;
}

• & to be manipulated in a reference variable

Program 2

how to Find pointer value is address of variable

#include <stdio.h>
#include <stdlib.h>

int main()
{
int a;        //assign int type a,but not initialized
int b=25;     //assign int type b,and initialized value 25
float c=3.45;     //assign float type c and initialized 3.45
printf(“address of a:%un”,&a);    //disply address of a in memory location , //&a address of a
printf(“address of a:%un”,&b);  //disply address of b in memory location
printf(“address of a:%un”,&c);  //disply address of c in memory location
int *p1;                //assign  a pointer of int type p1;
p1=&a;              //assign address of a to pointer p1
int *p2=&b;       //assign a pointer of int p2 and
 //assign address of b to pointer p2 same line
float *p3=&c;       //assign a pointer of int p3 and
//assign address of c to pointer p3
printf(“n”);
printf(“value of p1 is:%un”,p1);         //disply value of p1 which is address of a
printf(“value of p2 is:%un”,p2);        //disply value of p2 which is address of b
printf(“value of p3 is:%un”,p3);        //disply value 0f p3 which is address of c

return 0;
}

 

Advantages of pointers

pointer increased the execution speed of the program

Pointers reduced the length and complexity of a program

Pointer enables a variable that is defined outside the function

a pointer used to pass information back and forth between a function and it’s the reference point

Disadvantages of pointers in C language

Uninitialized pointers might cause a segmentation fault

pointers are slower than other variables

if sufficient memory is not available during runtime for the storage of pointers the program may crash

Related Links

Pointers in C++ Programming language

Pointer to pointer in C Programming Language

Pointer to pointer in C++ Programming Language

Pointers with one d array in C language

Structure with pointers in C Language

Structure with pointers in C++ Language

Pointers and one d array in C++