how to apply columnar transposition?

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hey guys,
i have a problem in columnar transposition cipher
I've made half of the code but i really have a serious problem in for loop
and here is the code

C#

string text = textBox1.Text;
double cols = double.Parse(textBox2.Text);
double len = text.Length;

string d;
if (cols > len)
{
    label3.Text = "cols must be less than text";

}
else
{
    double test = len / cols;
    if (test % 1 == 0)
    {
        double row = test;
        char[,] enc = new char[(int)cols, (int)row];
        char[,] matrix = new char[(int)row, (int)cols];
        char[] characters = text.ToCharArray();
        for (double i = 0; i < row; i++)
        {
            for (double j = 0; j < cols; j++)
            {
                matrix[(int)i, (int)j] = characters[(int)(i + j + i * 2)];
                MessageBox.Show(Convert.ToString(matrix[(int)i, (int)j]));
            }

        }
        for (double c = 0; c < cols; c++)
        {
            for (double r = 0; r < row; r++)
            {
                
                MessageBox.Show(Convert.ToString(matrix[(int)c, (int)r]));
                
            }
        }

can any one help me :(

Posted 28-Apr-12 12:30pm

mooraamoora

Updated 28-Apr-12 12:36pm

VJ Reddy

v2

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VJ Reddy 28-Apr-12 18:36pm

Edit: pre tag for C# code added.

[no name] 28-Apr-12 20:17pm

"serious problem" does not tell us anything. We can't read your mind.

1 solution

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VJ Reddy · Accepted Answer · 2012-04-28T14:57:00

Solution 1

As seen from the code given in the question

C#

double cols = double.Parse(textBox2.Text);
double len = text.Length;

cols is used for the matrix size, so it is preferable to have it as int.
The property text.Length is of type int and it can be used as it is and there is no need to assign to a local variable.

C#

double test = len / cols;
if (test % 1 == 0)

can be given as an else if like

C#

else if (len % cols != 0)
  label3.Text = "The text length shall be equal to rows * cols ";

The transposition can be done in the else block
By taking row, cols as int the cast (int) can be avoided.

Further for transpose
1. The matrix can be declared with text.Length /cols as rows and cols as columns.
2. Each element in the matrix can be assigned by using for loop on text like

C#

matrix[i/cols,i%cols]=text[i];

Posted 28-Apr-12 14:57pm

VJ Reddy

Updated 28-Apr-12 15:09pm

v2

Comments

Shahin Khorshidnia 29-Apr-12 2:20am

nice

VJ Reddy 29-Apr-12 11:10am

Thank you, Shahin.

mooraamoora 29-Apr-12 13:10pm

thanks very much for helping :)...finally done,
columnar transposition is a way you assign the value of textbox to 2-d array so that you can read the array column by column not as usual row by row, the problem I had was when I first assigned the textbox value to 1-D array, then assigning this array to 2-D array..every time it says array is outside bound, but finally I got it.
this is the new code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace w
{

public partial class Form1 : Form
{

public Form1()
{
InitializeComponent();
}

public void button1_Click(object sender, EventArgs e)
{

//lets goooooooooooooooooooooooooooo
string text = textBox1.Text;
double cols = double.Parse(textBox2.Text);
double len = text.Length;
double ind = 0;

if (cols > len)
{
label3.Text = "cols must be less than text";

}
else
{
double test = len / cols;

double row = Math.Ceiling(test);
label3.Text = ("number of rows = " + Convert.ToString(row));
char[,] matrix = new char[(int)row, (int)cols];
char[] characters = text.ToCharArray();
for (double i = 0; i < matrix.GetLength(0); i++)
{
for (double j = 0; j < matrix.GetLength(1); j++)
{
matrix[(int)i, (int)j] = characters[(int)(ind)];
ind++;

if (ind > len - 1)
{
break;
}
}

}
double ri = 0, cj = 0;
for (double i = 0; i <= matrix.GetLength(1); i++)
{
for (double j = 0; j <= matrix.GetLength(0); j++)
{
label7.Text += matrix[(int)ri, (int)cj];

ri++;
if (ri >= matrix.GetLength(0))
{
break;
}
}
ri = 0; cj++;
if (cj >= matrix.GetLength(1))
{
break;
}
}

}
}

private void button2_Click(object sender, EventArgs e)
{
string text = label7.Text;
double cols = double.Parse(textBox2.Text);
double len = text.Length;
double ind = 0;

if (cols > len)
{
label3.Text = "cols must be less than text";

}
else
{
double test = len / cols;

double row = Math.Ceiling(test);

char[,] matrix = new char[(int)row, (int)cols];
char[] characters = textBox1.Text.ToCharArray();
for (double i = 0; i < matrix.GetLength(0); i++)
{
for (double j = 0; j < matrix.GetLength(1); j++)
{
matrix[(int)i, (int)j] = characters[(int)(ind)];
ind++;
label8.Text += matrix[(int)i, (int)j];

if (ind > len - 1)
{
break;
}
}

}

}

}

private void Form1_Load(object sender, EventArgs e)
{

}
}
}

Day Star 29-Apr-12 15:00pm

how clear label
there are IndexOutOfRangeException in
matrix[(int)i, (int)j] = characters[(int)(ind)];
ind++;
label8.Text += matrix[(int)i, (int)j];