An example of how to print in columns from top to bottom in C++.

printcolumns.cpp

#include <iostream>   
#include <string>   

using namespace std;   

int main() {
	// Initial variables for the list
	int listSize = 26;
	int numOfColumns = 6;
	string list[] = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L",
		"M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};
	int lastRowCount = listSize % numOfColumns;

	// Determine number of rows to print to.
	int numOfRows;
	if (lastRowCount != 0) {
		numOfRows = listSize / numOfColumns + 1;
	} else {
		numOfRows = listSize / numOfColumns;
	}

	// Initial variables for the printer state.
	int currentRow = 1;
	int currentIndex = 0;
	bool printing = true;

	// Print the list from top to bottom until the printer is turned off.
	while (printing) {
		if (currentRow < numOfRows || lastRowCount == 0) {
			for (int column = 1; column < numOfColumns; column++) {
				cout << list[currentIndex] << "  ";
				if (column >= lastRowCount + 1 && lastRowCount != 0) {
					currentIndex += numOfRows - 1;
				} else {
					currentIndex += numOfRows;
				}
			}
			cout << list[currentIndex] << endl;
			currentRow++;
			currentIndex = currentRow - 1;
		} else {
			for (int index = 1; index <= lastRowCount; index++) {
				cout << list[currentIndex] << "  ";
				currentIndex += numOfRows;
			}
			printing = false;
			cout << endl; // Extra newline at the end to cleanly exit the program.
		}
	}
	return 0;
}

/* Output Example:
 * A  F  K  O  S  W
 * B  G  L  P  T  X
 * C  H  M  Q  U  Y
 * D  I  N  R  V  Z
 * E  J
 */