Nested For loop

Mar 17, 2013 at 12:17am
I am attempting to read a file with 2 numbers in it. The first indicates the number of rows the second, the number of columns.

So for a file (Data.txt) that contains the numbers 5 7, I want to display

0 0 0 0 0 0 0
1 1 1 1 1 1 1
0 0 0 0 0 0 0
1 1 1 1 1 1 1
0 0 0 0 0 0 0

and write that output to a file.

I can display the correct number of rows and columns but I can't figure out how to display alternating rows of 0's and 1's.

Any help would be greatly appreciated.


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#include <iostream>
#include <fstream>

using namespace std;

int main()
{
	ifstream inFile;		//declare file

	// declarations
	int rows;
	int cols;

	inFile.open("Data.txt");	//open file

	inFile >> rows;
	inFile >> cols;

	inFile.close();			//close file

	ofstream outputFile;
	outputFile.open("Printout.txt");

	for (int x = 0; x<rows; x++)
	{
		for (int y = 0; y<cols; y++)
		{
			cout << "X ";
		}
		cout << endl;
	}

	outputFile.close();

	system("pause");
	return 0;
}
Mar 17, 2013 at 12:42am
closed account (Dy7SLyTq)
in the nested for cout<< the counter % 2
Mar 17, 2013 at 12:58am
change cout<<'X'; to cout<<y%2; which is what DTScode said to do ... I think.
BTW X is not a string so you shouldn't use "X" but 'X'.. also 'X' is not a counter for the first loop ... it is 'x'.
Mar 17, 2013 at 1:06am
closed account (Dy7SLyTq)
yes that is what i meant. but first of all he did "X " which is a string and technically "X" is a string of one character and 'X' is a character
Mar 17, 2013 at 2:41am
Yes... I wasn't aware that that C++ allows a one character string ending with '\0' which is itself a character. However your solution to the above was nicely said and done...it remains to be seen if it bears fruit.
Mar 17, 2013 at 3:19am
Thanks. Changed the row counter to display the modulus division and its working great now!

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for (int x = 0; x<rows; x++)
	{
		for (int y = 0; y<cols; y++)
		{
			cout << (x % 2) << " " ;
			outFile << (x % 2) << " ";
		}
		outFile << endl;
		cout << endl;
	}
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