Show variable at every iteration

Question

#include <iostream>
using namespace std;

int main() {
    int sum(1), count(1);
    while (count <= 6) {
        sum += (2*count + 1);
        count++;
    } 
    cout << "sum = " << sum << endl; 

    return 0;
}

I have this C++ code that is suppose to print the sum of the six consecutive odd numbers, starting from the number 1. I need to fix it by using a variable tracing cout statement. I want the statement to show what the value of the variable and sum is at each iteration is. Please help.

Plus one for the nicely written question. How about you put a `cout` statement within the `while` loop? — Bathsheba, May 04 '17 at 06:58
Just add `cout << "sum = " << sum << " count = " << count << endl;` on the first line in the while loop. In this case it is important to use `std::endl` rather than `'\n'`, since the former will add a line break and also flush the stream. — Jonas, May 04 '17 at 06:59
@Jonas I don't think `std::endl` is really important here. The entire program will likely run faster than the update frequency of your screen ... — chtz, May 04 '17 at 07:33
@chtz I suppose that depends on the range, in this case it is short, so partly yes. On the other hand it is always appropriate to use `std::endl` when printing debug information, to avoid buffering. — Jonas, May 04 '17 at 07:37
@Jonas still, I would only flush, if I'd be worried that the execution between consecutive `cout` might crash (and thus lose information). But that is maybe more topic of e.g. http://stackoverflow.com/questions/213907/c-stdendl-vs-n — chtz, May 04 '17 at 07:51

Arya McCarthy · Answer 1 · 2017-05-04T07:09:38.723

2

Just put a cout inside your loop.

int main() {
    int sum(1), count(1);
    while (count <= 6) {
        sum += (2*count + 1);
        count++;
        cout << "current sum = " << sum << endl;
    } 
    cout << "sum = " << sum << endl; 

    return 0;
}

EDIT This is the form, at least, of how you'd go about doing it. This seems like a homework problem, so I'll let you handle the output formatting, as well as incorporating the variables you want.

edited May 04 '17 at 07:09

answered May 04 '17 at 06:59

Arya McCarthy

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I'm not downvoter. Why would you print after `count++`? – Jonas May 04 '17 at 07:03
I was. (i) the `cout` is in the wrong place in the loop, (ii) doesn't contain all the variables the OP wants to see, (iii) is a "give a fish" rather than "teach how to fish" answer, (iv) is the use of `endl` justified? – Bathsheba May 04 '17 at 07:06
(i) The asker was unclear about whether "at each iteration" meant before or after modification. (iii) Arguably, by not containing all the variables, it gives the OP an opportunity to fish. – Arya McCarthy May 04 '17 at 07:07
@Bathsheba I'm curious about your thoughts on the matter. – Arya McCarthy May 04 '17 at 07:11

Show variable at every iteration

1 Answers1