CS1101C Lab 1 (Even Week)

Long Addition

The name of your C program file must be called longadd.c, files with any other name will not be marked.

Preliminary

At this early stage of the course, you would probably have written a program that involves some integer addition. Below is an example of a very simple program add.c that accepts two integers from the user, computes and displays their sum in long addition format.

/**********************************************************************/
/* Matric Number: U051234A and U059876B                               */
/* Userid: u0501234 and u0509876                                      */
/* (For those doing pair programming, only ONE of you should submit   */
/*  your program. The other student should NOT submit.)               */
/* Lab: 1                                                             */
/* Lab Group Number: 99                                               */
/* Lab TA's Name: Who needs a lab TA when you're Bill Gates?          */
/* Lab Session Date: 15 February 2006                                 */
/* Lab Session Time: 0800 - 0945                                      */
/* Title: More Addition                                               */
/* Purpose: Calculates the sum of two integers.                       */
/**********************************************************************/


#include <stdio.h>

int main()
{
   /* Variable declaration */
   int num1, num2;
   int result;

   /* Get user input */
   printf("Enter the first number: ");
   scanf("%i", &num1);

   printf("Enter the second number: ");
   scanf("%i", &num2);

   /* Compute and pretty print result */
   result = num1 + num2;

   printf("  %4i\n"
          "+ %4i\n"
          "------\n"
          " %5i\n", num1, num2, result);

   return 0;
}

Throughout this lab exercise, we shall restrict the user input to non-negative numbers that do not exceed four digits in length, i.e. the user input must be between 0 to 9999 inclusive. A sample output from add.c is given below. User input is denoted in bold.

Enter the first number: 1234
Enter the second number: 9876

  1234
+ 9876
------
 11110

Long Addition With Carry

    1
  1234
+ 9876
------
     0

 1111
  1234
+ 9876
------
 11110

 11110
  1234
+ 9876
------
 11110

Initial Task

& gcc -Wall longadd.c -o longadd
$ longadd
Enter the first number: 1234
Enter the second number: 9876
 11110
  1234
+ 9876
------
 11110

$ longadd
Enter the first number: 9999
Enter the second number: 9999
 11110
  9999
+ 9999
------
 19998

$ longadd
Enter the first number: 123
Enter the second number: 98
   110
   123
+   98
------
   221

$ longadd
Enter the first number: 1234
Enter the second number: 0
     0
  1234
+    0
------
  1234

$ longadd
Enter the first number: 1234
Enter the second number: 2345
     0
  1234
+ 2345
------
  3579

$

Points to Note

• For simplicity, we assume that user input will always be within the range of permissible values, so there is no need to perform any explicit checks on the data entered by the user.
• Do not use any other data types except than int. That means you are not allowed to use double, float, etc. You are only allowed to use the int data type and nothing else.
• Do not use any selection statements (if, if-else, switch), repetition statements (while, do-while, for), nor the conditional operator ":?".

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