CSC231 Homework 3

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Assignment #3

This assignment is due on Wednesday Oct. 1st, at 11:59 p.m. plus one minute.

Problem #1

Same problem as we did in class. Below is the mystery program. Its output is listed in the header of the program.

/* mystery.cpp
// D. T.
// mystery program
// To compile and run this program:
//
//     g++ mystery.cpp
//     a.out
//
// The output of the program is the following
//
// 27001
// -31534
//
// With what positive values were x and y initialized
// at the beginning of the program.  Explain why.
// (a short int contains 16 bits)
*/

#include <stdio.h>

main() {

    short int x = ?????;
    short int y = ?????;


    x = x+y;
    printf( "%d\n", x );

    x = x+y;
    printf( "%d\n", x );
}

What two positive numbers are stored in x and y to create the output listed in the header?

Explain your answer.

Problem #2

Assume that we want to compute the Fibonacci series with a compiled program.

• How many terms can we correctly display if we use unsigned chars (8 bits) to store the Fibonacci terms?

• How many terms if we use unsigned short ints (16 bits)?

• How many terms if we use usigned ints (32 bits)?

• How many terms if we use long unsigned ints of 64 bits?

Explain carefully how you derive your answers. Prefered answers are answers that contain a program (in the language of your choice) demonstrating/illustrating in one way or another the answers to the various questions.

Problem #3

Assume that we write a C or C++ program that displays all the powers of 2 in this fashion:

unsigned int x = 1;

while ( x ) {
   printf ( "%d\n", x );
   x = x * 2;
}

• Is the loop infinite? Why?

• If it is not infinite, how many times does it go through, and how many terms does it print? Why? What is the last number displayed?