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c++listformatting

How do I get the last number to create a new line?

I am working on a lab for a C++ course. My current code gives me most but not all points available for this lab. I can't quite seem to get the code to print correctly. I've tried many possible ways of printing the code. On my closest attempts, the printed output seems to be missing a new line at the end of the last row. I would be most appreciative for any suggestions.

The assignment stated the following:

Hailstone sequence
Given a positive integer n, the following rules will always create a sequence that ends with 1, called the hailstone sequence:

If n is even, divide it by 2 If n is odd, multiply it by 3 and add 1 (i.e. 3n +1) Continue until n is 1 Write a program that reads an integer as input and prints the hailstone sequence starting with the integer entered. Format the output so that ten integers, each separated by a tab character (\t), are printed per line.

The output format can be achieved as follows: print(n, end='\t')

Ex: If the input is:
25

the output is:

25   76   38   19   58   29   88   44   22   11 
34   17   52   26   13   40   20   10   5    16 
8    4    2    1

My program below works but the auto-grader just wants me to have the exact match to what they have which has having a new line at the last number.

#include <iostream>
using namespace std;

int main() {
    int n; 
    int counter = 1;
    cin >> n;
    cout << n << "\t";

    while ( n >1) {
        if ( n%2 == 0) {
            n = n /2;
            cout << n << "\t";
        }
        else {
            n = 3 * n + 1;
            cout << n << "\t";
        }
        counter++;
        if ( counter % 10 ==0) {
            cout << endl;
        }
    }
    return 0;
}

Here is the auto grader telling what I need to fix:Zybooks auto-grader

I really don't understand, how it could be done?

Well I tried adding the "\t" new tab but it give me an error of not being a new line at every 10 number, so I changed the program back to endl: cout << n << "\t";

so I really don't understand why the auto grader is so finicky.

Solution

  • Note that all the numbers are separated by whitespace – the difference is just which whitespace is separating them.

    You're printing "number and tab" as one unit, then occasionally adding a linebreak.
    This make every line end with "number, tab, linebreak", and the last one with "number, tab".

    Instead print number, separator, number, separator, number, ...
    Finish the whole thing off with a linebreak after the loop.

    Something like this:

    int main() {
    int counter = 1;
    int n; 
    cin >> n;
    // Print the first number
    cout << n;
    while (n > 1) {        
        // Select a separator.
        if (counter % 10 == 0) {
            cout << endl;
        }
        else {
            cout << '\t';
        }
        // Determine the next number.
        if (n % 2 == 0) {
            n = n / 2;
        }
        else {
            n = 3 * n + 1;
        }
        // Print the number.
        cout << n;
        counter++;
    }
    cout << '\n';
}

    You can also shorten the loop a bit:

    while (n > 1) {   
    n = n % 2 == 0 ? n / 2 : 3 * n + 1;
    char separator = counter % 10 == 0 ? '\n' : '\t';
    cout << separator << n;
    counter++;
}