Pointers in C

A Pointer is a variable in C that contains address of another variable.

A pointer variable is denoted by

int *p; //This means p is a pointer to an integer variable

* is Value at Address operator

& is Address of Operator

int x =15; //x is an integer variable

int *ptr1 = &x //Now p contains the address of x..i.e ptr is a pointer to x

int **ptr2 = &ptr1 //And ptr2 contains the address of ptr1..so prt2 is a pointer to a pointer

#include <stdio.h>
#include <conio.h>

int main()
{
    int x=15;
    int *ptr1;
    int **ptr2;

    ptr1 = &x; //Now ptr contains the address of x
    ptr2 = &ptr1; //ptr2 contains the address of ptr

    printf("\nAddress of x = %u", &x);
    printf("\nValue of x = %d", x);
    printf("\nValue of x = %d", *(&x));

    printf("\n ");
    printf("\nAddress of ptr1 = %u", &ptr1);
    printf("\nValue of ptr1 / Address of x = %d", ptr1);
    printf("\nValue at address pointed by ptr1/Value of x = %d", *ptr1);

    printf("\n ");
    printf("\nAddress of ptr2 = %u", &ptr2);
    printf("\nValue of ptr2 / Address of ptr1 = %d", ptr2);
    printf("\nValue at address pointed ptr2 / Address of x= %d", *ptr2);
    printf("\nValue at address pointed by ptr1 which is pointed by ptr2/Value of x = %d", **ptr2);

    getch();
    return 0;
}

Snapshot of the o/p

C Program printing Celsius-Fahrenheit table

Hi Friends!!

This is the 2nd Program of our Temperature Conversion Table.

This time we converted from Celsius to Fahrenheit using the formula

F = C *(9/5)+32

where

C is Celsius
F is Fahrenheit 

Here is the program

/*Program printing Celsius-Fahrenheit table*/

#include <stdio.h>

#include <conio.h>

#define LOWER 0 /* lower limit of table */

#define UPPER 200 /* upper limit */

#define STEP 10 /* step size */

 

int main()

{

     int celc;

     printf(” Celsius\t Fahrenheit\n\n “);

     for (celc = LOWER; celc <= UPPER; celc = celc + STEP)

     printf(” %d \t   %6.1f\n”, celc, celc *(9.0/5.0)+32);

    

     getch();

     return 0;   

}

Screenshot of the o/p

Power Function in C

/*

  Program demonstrating Power Function

*/

 

#include<stdio.h>

#include<conio.h>

 

//Power Function Integer Version

int power(int base, int exponent)

{

      int i;

      int result = 1;

     

      for(i=1; i<=exponent; i++)

      {

               result = result * base;

      }

     

      return result; 

}

//Power Function Floating-Point Version

float powerfloat(float base, float exponent)

{

      float i;

      float result = 1.0;

     

      for(i=1; i<=exponent; i++)

      {

               result = result * base;

      }

     

      return result; 

}

 

int main()

{

     int a, b, c;

     a=2;

     b=3;

     printf(“\n ~~~Power Functions C~~~ \n”);

    

     printf(“\n %d to the power %d is %d”, a,b, power(a,b));

    

     printf(“\n 2.0 to the power 4.0 is %f”, powerfloat(2.0, 4.0));

     getch();

     return 0;  

}

Snapshot of the o/p

A Simple C Program

Hello Friends,

This is a very simple C Program demonstrating input, output using printf(), scanf() functions in C. It also shows how to write some simple functions in C without any argument or return type.

Level- Beginner

/*

  Program demonstrating Simple Functions, input, output in C

Hello.c

*/

 

#include<stdio.h>

#include<conio.h>

 

void hello_message()

{

     printf(“\n Hello World!! \n”); 

}

 

void bye_message()

{

     printf(“\n Good Bye World!!!\n”); 

}

 

void main()

{

     int num, a, b, c;

     a=5;

     b=7;

     printf(“\n ~~~Welcome to the world of C~~~ \n”);

     /*

     This is not allowed gives error

     printf(“\n Hello

    

     “);*/

    

     hello_message();

    

     printf(“\n Enter a Number : “);

    

     scanf(“%d”, &num);

    

     printf(“\n You entered %d”, num);

    

     printf(“\n c = %d (Garbage Value)”, c); //displays garbage value

     c=9;

     printf(“\n c = %d”, c);//o/p – 9

     printf(“\n a = %d”, a); //o/p – 5

    

     printf(“\n Experiments with printf \n”);

    

     printf(“\n number = %d”, 3); // o/p- 3

     printf(“\n a+b = %d”, a+b); //o/p -12

     printf(“\n a*b+c = %d”, a*b+c); //o/p-44

    

     printf(“\n Experiments with scanf \n”);

    

     printf(“\n Enter three Numbers : “);

     scanf(“%d %d %d”, &a, &b, &c);

     printf(“\n a = %d, b = %d, c = %d “, a,b,c);

     

     printf(“\n Enter three Numbers (separated by commas) : “);

     scanf(“%d, %d, %d”, &a, &b, &c);

     printf(“\n a = %d, b = %d, c = %d “, a,b,c);

    

     bye_message();

     getch();   

}

 Snapshot of the o/p