Thread: C++ - loops

I cannot understand this exercise:

"Write a program that computes a running sum of inputs from the user, terminating when the user gives an input value of 0"

I do not understand what I'm supposed to do here.

It sounds like the general algorithm is supposed to be like this:

1. Read number from the user
2. If that number is zero, exit. Otherwise, add it to a sum variable and go back to #1.

Ok, I will try it.

This should get you started in the right direction

Code:

#include <iostream>

using namespace std;



int main()
{
    int num = 0;
    int num2 = 0;
    int total = 0;
    do
    {
    cout << "Enter a number: " << endl;
    cin >> num;
    cout << "Enter a number: " << endl;
    cin >> num2;
    total += num + num2;
    }
    while(num || num2 != 0);

cout << total << endl;

return 0;



}

Code:

while(num || num2 != 0);

What are you expecting this line to do?

And this could have been done with a single input variable.

Originally Posted by Matticus

And this could have been done with a single input variable.

True. Remove the second variable, it achieves the same result with only one variable.

Code:

int main()
{
    int num = 0;
    int total = 0;
    
    do{
        cout << "Enter a number: " << endl;
        cin >> num;
        
        total+=num;
    
    }while(num != 0);
    
    cout << total << endl;

    system("pause"); 
    return 0;
}

Originally Posted by Matticus

Code:

while(num || num2 != 0);

What are you expecting this line to do?

And this could have been done with a single input variable.

Note I said "This should get you started in the right direction" which implies I put it there knowingly, we could argue for hours how this program could be done better and more efficiently but that would be counter productive. But I accept your input yes, it could be done much better.

Originally Posted by aejr120

True. Remove the second variable, it achieves the same result with only one variable.

Code:

int main()
{
    int num = 0;
    int total = 0;
    
    do{
        cout << "Enter a number: " << endl;
        cin >> num;
        
        total+=num;
    
    }while(num != 0);
    
    cout << total << endl;

    system("pause"); 
    return 0;
}

Just a little tip adding system("pause") will increase your file size substantially, you can replace it with something like this

Code:

cout << "Press enter to exit: "
char x;
cin x;

Side notence yes I know I could use better code than this or read for a specific key, but this will suffice.

Originally Posted by Dynamic

Note I said "This should get you started in the right direction" which implies I put it there knowingly, we could argue for hours how this program could be done better and more efficiently but that would be counter productive. But I accept your input yes, it could be done much better.

You didn't answer my question, though.

And how is this the "right direction"? This specific program might get lucky, but if we change the sentinel value to, say, -1, you have at least two major issues.

Your sentinel value gets factored into the sum, and the syntax of your "while()" loop is wrong.

Originally Posted by Matticus

You didn't answer my question, though.

And how is this the "right direction"? This specific program might get lucky, but if we change the sentinel value to, say, -1, you have at least two major issues.

Your sentinel value gets factored into the sum, and the syntax of your "while()" loop is wrong.

Hence saying right direction, or I am suppose to give this person a complete working solution for their college assignment?

IMHO, examples with incorrect syntax is not the right direction. But that's just my opinion - you're free to disagree.