Display data in two columns c++ - c++

Question

I am trying to display the same data but in two columns, so after school week 19, the data should be displayed in the columns to the right of the table until the total school weeks is reached i.e. 36. Below is the code:
#include "stdafx.h"
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;
int const schoolWeeks = 37;
string week[] = { "A", "B", "C", "D" };
int num = 0;
int main()
{
cout << left << setw(9) << setfill(' ') << "Week " << left << setw(9) << setfill(' ')<< "Menu" << left << setw(9) << setfill(' ') << "Week " << "Menu" << endl;
for (int i = 1; i < 20; i++)
{
cout << left << setw(9) << setfill(' ')<< i << week[num] << endl;
num = num + 1;
if (num == 4)
{
num = 0;
}
}
for (int i = 20; i < schoolWeeks; i++)
{
cout << left << setw(9) << setfill(' ') << i << week[num] << endl;
num = num + 1;
if (num == 4)
{
num = 0;
}
}
}

Answer 1

Standard output with std::cout is based on the idea of a stream of data. Remember, it's called "iostream" for a reason. This means once you have written something to std::cout, you simply cannot "go back" a few lines and add something.
Consider piping in a Linux shell or on the Windows command line. It's possible to redirect the output of your program to be the input of another program, which could then do any imaginable thing with it, e.g. sending it over the internet:
myprogram.exe > otherprogram.exe
How could you possibly add something to an already written line in such a scenario?
Considering all of this, it becomes clear that the only viable solution is to know in advance the contents of every line. You cannot wait until line 19 before thinking about the second column, you must do it right away. In other words, first print week 1 and week 19, then week 2 and week 20, then week 3 and week 21, and so on. See the pattern? It's always "week X in column one, week X+18 in column two". And that's pretty much the solution.
Here's a quickly written loop adhering to the style of your existing code:
for (int i = 1; i < 19; i++)
{
cout << left << setw(9) << setfill(' ')<< i << week[num]
<< left << setw(9) << setfill(' ') << " " << (i + 18) << " "
<< left << setw(9) << setfill(' ') << " " << week[num]
<< endl;
num = num + 1;
if (num == 4)
{
num = 0;
}
}
The manipulators like std::setw or std::setfill could probably use some improvement, but the point is that:
The loop only counts from 1 to 18.
The body performs the output for i and for i + 18.