#include <stdio.h>
int main()
{
   int num;
   printf("Enter a integer: ");  
   scanf("%d",&num);  /* Storing a integer entered by user in variable num */
   printf("You entered: %d",num);
   return 0;
}

Enter a integer: 25
You entered: 25

/*C programming source code to add and display the sum of two integers entered by user */

#include <stdio.h>
int main( )
{
   int num1, num2, sum;
   printf("Enter two integers: ");
   scanf("%d %d",&num1,&num2); /* Stores the two integer entered by user in variable num1 and num2 */

   sum=num1+num2;      /* Performs addition and stores it in variable sum */
   printf("Sum: %d",sum);  /* Displays sum */
   return 0;
}

Enter two integers: 12
11
Sum: 23

/* C programming source code to add and display the sum of two integers entered by user using two variables only. */

#include <stdio.h>
int main( )
{
   int num1, num2, sum;
   printf("Enter a two integers: ");
   scanf("%d %d",&num1,&num2);     
   num1=num1+num2; /* Adds variables num1 and num2 and stores it in num1 */
   printf("Sum: %d",num1); /* Displays value of num1 */
   return 0;
}

/*C program to multiply and display the product of two floating point numbers entered by user. */

#include <stdio.h>
int main( )
{
  float num1, num2, product;
  printf("Enter two numbers: ");
  scanf("%f %f",&num1,&num2);        /* Stores the two floating point numbers entered by user in variable num1 and num2 respectively */
  product=num1*num2;  /* Performs multiplication and stores it */
  printf("Product: %f",product);
  return 0;
}

Enter two numbers: 2.4
1.1
Product: 2.640000

/* Source code to find ASCII value of a character entered by user */

#include <stdio.h>
int main(){
   char c;
   printf("Enter a character: ");
   scanf("%c",&c);        /* Takes a character from user */
   printf("ASCII value of %c = %d",c,c);
   return 0;
}

Enter a character: G
ASCII value of G = 71

/* C Program to compute remainder and quotient  */

#include <stdio.h>
int main(){
   int dividend, divisor, quotient, remainder;
   printf("Enter dividend: ");
   scanf("%d",&dividend);
   printf("Enter divisor: ");
   scanf("%d",&divisor);
   quotient=dividend/divisor;           /*  Computes quotient */
   remainder=dividend%divisor;          /* Computes remainder */
   printf("Quotient = %d\n",quotient);
   printf("Remainder = %d",remainder);
   return 0;
}

Enter dividend: 25
Enter divisor: 4
Quotient = 6
Remainder = 1

/* C Program to compute and display remainder and quotient  using only two variables */

#include <stdio.h>
int main(){
 int dividend, divisor;
 printf("Enter dividend: ");
 scanf("%d",&dividend);
 printf("Enter divisor: ");
 scanf("%d",&divisor);
 printf("Quotient = %d\n",dividend/divisor);/* Computes and displays quotient */
 printf("Remainder = %d",dividend%divisor); /* Computes and displays remainder */
 return 0;
}

temp = sizeof(operand);
/* Here, temp is a variable of type integer,i.e, sizeof() operator 
  returns integer value. */

/* This program computes the size of variable using sizeof operator.*/

#include <stdio.h>
int main(){
   int a;
   float b;
   double c;
   char d;
   printf("Size of int: %d bytes\n",sizeof(a));
   printf("Size of float: %d bytes\n",sizeof(b));
   printf("Size of double: %d bytes\n",sizeof(c));
   printf("Size of char: %d byte\n",sizeof(d));
   return 0;
}

Size of int: 4 bytes
Size of float: 4 bytes
Size of double: 8 bytes
Size of char: 1 byte

#include <stdio.h>
int main(){
  int a;
  long int b;                /* int is optional. */
  long long int c;            /* int is optional. */
  printf("Size of int = %d bytes\n",sizeof(a));
  printf("Size of long int = %ld bytes\n",sizeof(b));
  printf("Size of long long int = %ld bytes",sizeof(c));
  return 0;
}

Size of int = 4 bytes
Size of long int = 4 bytes
Size of long long int = 8 bytes

#include <stdio.h>
int main(){
   float a, b, temp;
   printf("Enter value of a: ");
   scanf("%f",&a);
   printf("Enter value of b: ");
   scanf("%f",&b);
   temp = a;    /* Value of a is stored in variable temp */
   a = b;       /* Value of b is stored in variable a */
   b = temp;    /* Value of temp(which contains initial value of a) is stored in variable b*/
   printf("\nAfter swapping, value of a = %.2f\n", a);
   printf("After swapping, value of b = %.2f", b);
   return 0;
}

Enter value of a: 1.20
Enter value of b: 2.45

After swapping, value of a = 2.45
After swapping, value of b = 1.2