Question

Write some C++ program segments that solves the indicated tasks (you do not have to write a complete program, nor be concerned about "good" output; a small code segment will be enough).

a) A program that gets a double number from the user, decides whether that number is positive, negative, or zero and display its decision on the screen.


a) A function isPositive that takes as input a double number and returns the integer 1 if the number is positive, and zero otherwise.


b) A program to print all even integers between 1 and 30 on the screen


c) A program to reads a real number as input and adds it to a running total until the user enters the number -1. At that time the program should print out the final sum (not including, of course, the number -1).

Answer 1

Please look at my code and in case of indentation issues check the screenshots.

---------------main1.cpp---------------

#include <iostream>
using namespace std;

/*
a) A program that gets a double number from the user, decides whether that number is positive, negative, or zero and display its decision on the screen.
*/

int main()
{
   double number;
   cout << "Enter a double number: ";
   cin >> number;                           //read double number

   if(number > 0)                           //make a decision using if else
       cout << "The number " << number << " is a positive number" << endl;
   else if(number < 0)
       cout << "The number " << number << " is a negative number" << endl;
   else
       cout << "The number " << number << " is a zero" << endl;
   return 0;
}

---------------main2.cpp---------------

#include <iostream>
using namespace std;

/*
A function isPositive that takes as input a double number and returns the integer 1 if the number is positive, and zero otherwise.
*/

int isPositive(double number)
{
   if(number > 0)
       return 1;
   else
       return 0;
}

int main()
{
   double number;
   cout << "Enter a double number: ";
   cin >> number;                           //read double number

   int value = isPositive(number);           //call the function to make a decision
   if(value == 1)                          
       cout << "The number " << number << " is a positive number" << endl;  
   else
       cout << "The number " << number << " is not a positive number" << endl;
   return 0;
}

---------------main3.cpp---------------

#include <iostream>
using namespace std;

/*
A program to print all even integers between 1 and 30 on the screen
*/

int main()
{
   cout << "The even numbers between 1 to 30 are: ";
   for(int i = 2; i <= 30; i = i + 2){                       //start i from 2, loop until i <= 30, increment i by 2
       cout << i << " ";
   }
   cout << endl;
   return 0;
}

---------------main4.cpp---------------

#include <iostream>
using namespace std;

/*
A program to reads a real number as input and adds it to a running total until the user enters the number -1.
At that time the program should print out the final sum (not including, of course, the number -1)
*/

int main()
{
   double number;
   double sum = 0;
   cout << "Enter a real number: ";
   cin >> number;                           //read first number  
   while(number != -1){                   //loop breaks if number is equal to -1
       sum = sum + number;                   //compute sum
       cout << "Enter a real number: ";
       cin >> number;                       //read next number          
   }

   cout << "The sum of the numbers is " << sum << endl;    //print the sum
   return 0;
}

--------------Screenshots-------------------

------------------Output-----------------

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