Question

Write a loop using a sentinel value. The sentinel value will be "999" and when this number is entered, the loop will end. The user will enter a number. You will examine the number and determine if it is even or odd. If it is even, you will add one to the even counter. If it is odd, add one to the odd counter. When the loop has ended, print out a message telling how many even and odd numbers were entered.

Answer 1

The c++ program is shown below.

#include <iostream>

using namespace std;

int main()

{

// variables declared for counter and input

int count_even, count_odd, num;

// count initialized to 0

count_even = 0;

count_odd = 0;

cout << " This program calculates the number of even and odd numbers entered by the user. Enter 999 to quit. " << endl;

cout << " Enter a positive number. " << endl;

cin >> num;

// loop will terminate if the user inputs sentinel value

while( num != 999 )

{

// for even numbers, 1 is added to count_even else count_odd

if( num%2 == 0 )

count_even = count_even + 1;

else

count_odd = count_odd + 1;

cout << " Enter a positive number. " << endl;

cin >> num;

}

cout << count_even << " even numbers entered. " << count_odd << " odd numbers entered. " << endl;

return 0;

}

OUTPUT

Enter a positive number.

34

Enter a positive number.

56

Enter a positive number.

78

Enter a positive number.

3

Enter a positive number.

5

Enter a positive number.

7

Enter a positive number.

9

Enter a positive number.

1

Enter a positive number.

999

4 even numbers entered. 5 odd numbers entered.

Step-by-step explanation:

First, the variables are declared.

int count_even, count_odd, num;

The counter variables are initialized to 0.

count_even = 0;

count_odd = 0;

The loop continues to run till the user enters the sentinel value of 999. User input is not validated for positive or negative number.

while( num != 999 )

{

if( num%2 == 0 )

count_even = count_even + 1;

else

count_odd = count_odd + 1;

cout << "Enter a positive number. " << endl;

cin >> num;

}

For every user input, if the input is not a sentinel value, the loop is executed otherwise, the loop is terminated.