Category: Languages

The programming directory

Overloading methods – c#

Overloading a method in a class is making a method name be able to take different parameters and return values. A good example would be if you had a method that was adding a passed value to a internal private variable, but wanted to be able to do different processes if the value is a integer /double / floating point number. To overload a method as above the code would be similar to this

public void addNumber(int intValue)
{
....
}
 
public void addNumber(double doubleValue)
{
...
}

Here is a basic overloading method, to just print out to the console a message.

using System;
 
namespace inheritance
{
 
	class firstClass
	{
		public void printClassName()
		{
			Console.WriteLine("FirstClass");
		}
 
		// overloading the method printClassName
		public void printClassName(String additionalMessage)
		{
			Console.WriteLine("FirstClass  : " + additionalMessage);
		}
	}
 
	class MainClass
	{
		public static void Main(string[] args)
		{
			firstClass first = new firstClass();
			first.printClassName();
			// call the overloaded function to pass in a message to print out.
			first.printClassName("overloaded");
		}
	}
}

output would be

FirstClass
FirstClass  : overloaded

Inheritance and over riding methods – c#

Inheritance allows one class to be expanded on in further classes. The protected method/variables in the base class is accessible to the inherited classes, but the private method/variables are not.

Here is a very basic inheritance

using System;
 
namespace inheritance
{
 
	class firstClass
	{
		public void printFirstOut()
		{
			Console.WriteLine("Hi from the first class");
		}
 
	}
 
	class secondClass : firstClass
	{
		public void printSecondOut()
		{
			Console.WriteLine("Hi from second class");
		}
	}
 
	class MainClass
	{
		public static void Main(string[] args)
		{
			secondClass sec = new secondClass();
			// can still call the first class method
			sec.printFirstOut();
 
			// and also the second class method of course
			sec.printSecondOut();
 
			firstClass first = new firstClass();
			// can print out the first class method
			first.printFirstOut();
 
			// but first does not have knowledge of the printSecondOut() method
			// because it is not linked. Error below.
//			first.printSecondOut();
			// Description=Type `inheritance.firstClass' does not contain a definition for `printSecondOut' 
			// and no extension method `printSecondOut' of type `inheritance.firstClass' 
			// could be found (are you missing a using directive or an assembly reference?)(CS1061)]
		}
	}
}

output would be

Hi from the first class
Hi from second class
Hi from the first class

Over riding of methods from the base class can happen to make a version 2 of a class as such.

The printClassName() method below is override’d in the secondClass and it requires to have the word ‘new’ because then that tells the compiler to over ride the method in the secondclass, it may come back with a warning in the compiling of this project to say that there is a same method name in the inherited class.

using System;
 
namespace inheritance
{
 
	class firstClass
	{
		public void printClassName()
		{
			Console.WriteLine("FirstClass");
		}
	}
 
	class secondClass : firstClass
	{
		new public void printClassName()
		{
			Console.WriteLine("SecondClass");
		}
	}
 
	class MainClass
	{
		public static void Main(string[] args)
		{
			firstClass first = new firstClass();
			first.printClassName();
 
			secondClass sec = new secondClass();
			sec.printClassName();
		}
	}
}

output would be

FirstClass
SecondClass

Wordseach c# – WordToSearchGrid

The WordToSearchGrid is basically the last part of the beginning part of the wordsearch project. It brings together the grid class (which it in inheriting from) and the word class.

The direction of the words are like a compass directions, north, south, east and west and the north east, south east, north west and south west. Their are 8 directions in total that a word can take.

The getWords function gets the words to search for.

For testing, I have overloaded the createRowGrid method in the grid class. So just need to comment out the method in the class below.

I have already done a version of this code in PHP and more of a detailed information about the createSearchGrid method is on this PHP WordToSearchGrid webpage. But hopefully the comments are good enough in the code below to explain why and what is happening.

To compile up the whole thing, the Word and Grid classes will need to be included in the source code.

using System;
using System.Xml;
using System.Collections;
 
namespace wordsearchcsharp
{
	/*
	 * WordToSearchGrid extends / Inheritance from the base Grid class
	 * so that the basics of the grid class can be used e.g. creation of a random grid etc.
	 */
 
	class WordToSearchGrid : Grid
	{
		// I like to use privates instead of protected variables so that each class
		// has access to there private variables
		private String[] _words;
 
		// the constructor to call the base constructor would use 
		public WordToSearchGrid() : base() {}
		public WordToSearchGrid(int size) : base (size) {}
 
                // create a empty grid - override ('new') the base class method.
		public override char[] createGridRow()
		{
			char[] retArray = new char[returnSize()];
			for (int i =0; i < returnSize(); i++)
			{
				retArray[i] = ' ';
			}
			return retArray;
		}
 
		// get the words from the words class into this class.
		public void getWords(String[] wordsArray)
		{
			this._words = wordsArray;
		}
 
	    // print out the words to search for that have been inserted into the grid
		public void printTheWordsToSearch()
		{
			Console.WriteLine("Words to search for : ");
			foreach (string st in this._words)
			{
				Console.WriteLine(st);
			}
		}
 
		// insertIntoGrid at point position X (pX) and Y (pY) with the word and direction
		public void insertIntoGrid(int pX, int pY, String word, int direction)
		{
			int wordLen = word.Length;
 
			// move the starting point of the word to the correct place within the grid
			// the default is north and west, so will need to correct for south and east directions.
			if (direction >= 4 && direction <=6) pY-=(wordLen-1);
			if (direction >= 2 && direction <=4) pX-=(wordLen-1);
 
			// 1 = north , 2 = north east, 3 = east, 4 = south east, 5 = south, 6 = south west, 7 = west, 8= north west
			// process each letter of the word and move the position to insert in the correct direction
			for (int i =0; i < wordLen; i++)
			{
				insertCharIntoGrid(pX, pY, word[i]);
				switch (direction)
				{
			      case 1 : pY--; break;
			      case 2 : pY--; pX++; break;
			      case 3 : pX++; break;
			      case 4 : pY++; pX++; break;
			      case 5 : pY++; break;
			      case 6 : pY++; pX--; break;
			      case 7 : pX--; break;
			      case 8 : pY--; pX--; break;
			      default : break;
				}
			}
		}
 
	    // createSearchGrid, will insert the words onto a blank grid (for testing).
	    // in random places and directions.
		public void createSearchGrid()
		{
			Random rand = new Random((int)DateTime.Now.Ticks);
			int wordLen, direction, pointX, pointY, space, spaceY, spaceX;
			// loop thought the words to insert
			for (int i =0; i < _words.Length; i++)
			{
				wordLen = _words[i].Length;
				// if the word is larger than the size of the grid, it cannot be inserted.
 
			    // NOTE : at present there is no intersection (crossing search words) shall do in the next version
				if (wordLen < _size)
				{
			        //need to pick a direction and also a point on the grid.
			        // also need to try and place the word onto the grid x amount of times else break out.
					direction = rand.Next(1, _size);
					pointX = rand.Next(1, _size);
					pointY = rand.Next(1,_size);
 
				    // the remainder of the subtracting the points from the size of grid will basically say how much space is required
					space = _size - wordLen;
 
				    // check against the direction and the size of the word against where it is on the poistion in the grid
				    // 1 = north , 2 = north east, 3 = east, 4 = south east, 5 = south, 6 = south west, 7 = west, 8= north west
				    // from the points point of view.
					spaceY = _size - pointY;
					spaceX = _size - pointX;
 
				    // if the direction is not east or west, and there is not enought space, move the insertion pointY difference
					// north and south
					if (!((direction == 7) || (direction == 3)))
					{
						if (spaceY > space)
							pointY+= (spaceY - space);
					}
 
			        // if the direction is not north or south and there is not enought space, move the insertion pointX difference
			        // east and west.
					if (!((direction == 1) || (direction == 5)))
					{
						if (spaceX > space)
							pointX+= (spaceX - space);
					}
					this.insertIntoGrid(pointX, pointY, _words[i], direction);
				}
				else
				{
					Console.WriteLine("Word : " + _words[i] + " is too long for the grid of size " + _size);
				}
			}
		}
 
	}
 
	class MainClass
	{
		public static void Main(string[] args)
		{
			Word word = new Word("words.xml",3);
			WordToSearchGrid gridWithWords = new WordToSearchGrid();
 
			// place the words into the WordToSearchGrid 
			gridWithWords.getWords(word.returnWords());
			// create a search grid with the words passed above.
			gridWithWords.createSearchGrid();
			// print out the grid		
			gridWithWords.printOutGrid();
			// print out the words to search
			gridWithWords.printTheWordsToSearch();
			// of course could have used the Word class
			// but since this is the WordToSearchGrid, so just placed one method in there as well.
			word.printOutWords();
		}
	}
}

and a example output would be with the testing blank grid created.

The Grid
0 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 =  8 =  9 =  10 =  
1 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 =  8 = o9 =  10 =  
2 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 =  8 =  9 = l10 =  
3 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 =  8 =  9 =  10 = d
4 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 =  8 =  9 =  10 =  
5 ..0 =  1 =  2 =  3 =  4 = s5 =  6 =  7 =  8 =  9 =  10 =  
6 ..0 =  1 =  2 =  3 =  4 =  5 = o6 =  7 =  8 =  9 =  10 =  
7 ..0 =  1 =  2 =  3 =  4 =  5 =  6 = l7 =  8 =  9 =  10 = w 
8 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 = e8 =  9 =  10 = a 
9 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 =  8 =  9 =  10 = s
10 ..0 =  1 =  2 =  3 =  4 =  5 =  6 =  7 =  8 =  9 =  10 =  
Words to search for : 
old
was
sole
Words : (  0 = old  1 = was  2 = sole)

and output without the testing blank grid

The Grid
0 ..0 = u1 = r2 = s3 = f4 = x5 = b6 = a7 = o8 = m9 = j10 = m
1 ..0 = s1 = s2 = o3 = l4 = e5 = k6 = h7 = g8 = v9 = e10 = h
2 ..0 = a1 = y2 = l3 = a4 = q5 = a6 = q7 = i8 = x9 = s10 = i
3 ..0 = t1 = j2 = q3 = x4 = r5 = b6 = s7 = m8 = g9 = f10 = d
4 ..0 = m1 = t2 = v3 = u4 = r5 = c6 = t7 = q8 = o9 = s10 = w
5 ..0 = g1 = f2 = c3 = s4 = r5 = d6 = v7 = u8 = x9 = f10 = r
6 ..0 = n1 = c2 = s3 = q4 = v5 = t6 = f7 = w8 = a9 = t10 = s
7 ..0 = h1 = m2 = y3 = o4 = v5 = u6 = h7 = b8 = i9 = h10 = n
8 ..0 = b1 = w2 = e3 = m4 = e5 = h6 = j7 = f8 = d9 = t10 = i
9 ..0 = u1 = i2 = j3 = k4 = w5 = w6 = l7 = k8 = l9 = h10 = c
10 ..0 = o1 = s2 = o3 = i4 = w5 = x6 = n7 = o8 = o9 = t10 = w
Words to search for : 
he
sole
old
Words : (  0 = he  1 = sole  2 = old)

Use the new keyword if hiding was intended(CS0108)

If you are using the inheritance in c# and are wanting to override (hide) the base class method but forget to use the ‘new’ keyword then you will get the warning.

Use the new keyword if hiding was intended(CS0108)

An example of this in coding syntax would be something like

class BC 
{
  public void DisplayMe()
  {
    System.Console.WriteLine("Display me from BC");
  }
}
// inherited class from BC
class NewBC : BC 
{
  public void DisplayMe()
  {
    System.Console.WriteLine("Display me from the NewBC :) yeppy");
  }
}
 
NewBC NBC = new NewBC();
NBC.DisplayMe();

and the output would be

Display me from the NewBC :) yeppy

If you note that the base class in the NBC has not been called from the NBC.DisplayMe() method e.g. “Display Me from BC”

But you will get the warning message from the compiler

Use the new keyword if hiding was intended(CS0108)

So all you do is to put the keyword ‘new’ before the overriding method e.g.

// inherited class from BC
class NewBC : BC 
{
  new public void DisplayMe()
  {
    System.Console.WriteLine("Display me from the NewBC :) yeppy");
  }
}

Wordsearch c# – Word class

I am just doing a test/comparsion between the different ways of getting a similar code syntax to work in different languages for a similar project idea. The main project idea is wordsearch grid with words inserted onto the grid, I have already done a basic php version and here is the word class in php word. Below there is a full class version of whole class, but also some parts that I have expanded to try and explain in more detail.

This code will return a String array from a ArrayList type. The ToArray changes the ArrayList to type of string then the “as string[]” returns the list of string as a string array.

			return (arrayL.ToArray(typeof(string)) as string[]);

Here is the word class in c#, I have added allot of code comments to give details of what is happening.

using System;
using System.Xml;
using System.Collections;
 
namespace wordsearchcsharp
{
	class Word 
	{
		private String[] _words;
 
	 	public  Word() : this("words.xml", 5) {}
 
		public Word(string wordsOrFilename, int maxSearchNum)
		{
			this._words = new String[maxSearchNum];
			// just load from a file the words to search, instead of input as well.
			String[] loadedWords = loadWords(wordsOrFilename);
 
			// create the searchable words from the loadedwords array.
			this._words = this.searchableWords(loadedWords, maxSearchNum);
		}
 
		private String[] loadWords(string filename)
		{
			XmlTextReader fileReader = new XmlTextReader(filename);
 
			ArrayList fileArray = new ArrayList();
 
			while (fileReader.Read())
			{
				// get the NodeType from the XML reader, different types
				// Element = name of element
				// Text = the actual text/word
				// End Element = end of the element name
			    switch (fileReader.NodeType) 
			    {
					// if there is a word in the file e.g. not a end/element
					  case XmlNodeType.Text: 
							fileArray.Add(fileReader.Value);
				            break;
			    }
			}
			// change the ArrayList into a String[] array using the ToArray method
			return (fileArray.ToArray(typeof(string)) as string[]);
		}
 
		// create a list of words from the words passed in and also 
		// the maximum number is the maxSearchNum.
		private String[] searchableWords(String[] words, int maxSearchNum)
		{
			ArrayList returnWords = new ArrayList();
 
			// if the maxsearch value is greater or equal to the number of words to search for 
			// just return the words string[].
			if (words.Length <= maxSearchNum)
			{
				return words;
			}
			else
			{
				// create a good seed for the random generator.
				Random randGen = new Random((int)DateTime.Now.Ticks);
				int randomNum;
				// randomly pick out words from the array
				for (int i = 0; i < maxSearchNum; i++)
				{
					// pick a random number
					randomNum = randGen.Next(0, words.Length);
					// add to the array list to return
					returnWords.Add(words[randomNum]);
					// rebuild the array with removing the random number generated.
					words = rebuildArray(words, randomNum);
				}
			}
			// convert back to the String[] 
			return (returnWords.ToArray(typeof(string)) as string[]);
		}
 
		private String[] rebuildArray(String[] rebuildSt, int numberToTakeOut)
		{
			ArrayList arrayL = new ArrayList();
			// out of range error.
			if (rebuildSt.Length < numberToTakeOut)
			{
				return rebuildSt;
			}
			else
			{
				for (int i =0; i < rebuildSt.Length; i++)
				{
					// only add in the words that are not the
					// numberToTakeOut word from the array
					if (i != numberToTakeOut)
					{
						arrayL.Add(rebuildSt[i]);
					}
				}
			}
			return (arrayL.ToArray(typeof(string)) as string[]);
		}
 
		public void printOutWords()
		{
			Console.Write("Words : (");
			for (int i = 0; i < this._words.Length; i++)
			{
				Console.Write("  " + i + " = " + this._words[i]);
			}
			Console.Write(")\n");
		}
 
		public String[] returnWords()
		{
			return this._words;
		}
	}
 
	class MainClass
	{
		public static void Main(string[] args)
		{
			Word word = new Word("words.xml",3);
                        word.printOutWords();
		}
	}
}

and a output would be

Words : (  0 = he  1 = old  2 = sole)

Monodevelop – system.xml error

I use monodevelop to create my c# applications etc and just noticed that if you want to have more references to assemblies like System.Xml then you will have to add them via the GUI.

For example, if you get the error.

Description=The type or namespace name `Xml' does not exist in the namespace `System'. Are you missing an assembly reference?(CS0234)

then you will need to add the System.Xml assembly reference into the GUI solutions manager to compile in that assembly.

If you goto Solutions box -> References -> (Right click) Edit References. In the packages tab scroll down in the list and find the System.Xml and add it to the solution. Compile again and it will work :).. well you may get other errors but at least this one is sorted.

If you do not have the Solutions box, goto the main monodevelop menu View -> Solution.

Wordsearch – c# Grid class

When coding in c#/csharp, I use monodevelop. Here is the wordsearch base Grid class in c#, I am coding in different languages just for fun as such, but here is the main idea for the wordsearch. I have already done a basic version in php which is at the present state in creating a grid (but without any intersection of words with others). But here is the Grid class in php, and below is the similar setup in csharp.

The main class, is where the application executes from, it is very similar to c++ in that there is a main function

public static void Main(string[] args)

which takes the string[] args as a parameter, which is what is passed in on the command line.

Anyway, here is the code.. I have added in some comments to what the code is doing.

using System;
 
namespace wordsearchcsharp
{
	class Grid {
		protected int _size = 0;
		protected char[][] _grid;
 
		// the ": this(11)" means call the Grid(int size) constructor with 11 as a parameter
		public Grid() : this(11)
		{
			// default size of a grid = 11
		}
 
		public Grid(int size)
		{
			this._size = size;
			// create a new row (Y direction)
			this._grid = new char[this._size][];
			for (int i =0; i < this._size; i++)
			{
				// create new X direction row.
				this._grid[i] = createGridRow();
			}
		}
 
		// createGridRow, this can be inherited and thus altered to create any type of character in the grid 
		public virtual char[] createGridRow()
		{
			// need to insert a good seed into the random generator.. else same characters
			Random random = new Random((int)DateTime.Now.Ticks);
 
			// create a new row (X direction) and place characters into it.
			char[] grid_insert = new char[this._size];
			for (int i = 0; i < this._size; i++)
			{
				// 0 - 25 = alphabet, and also +97 is the ascii start for the character 'a'
				grid_insert[i] = (char)(random.Next(0,25)+97);
			}
			return grid_insert;
		}
 
		// printOutGrid, will print out the grid created above.
		// i = Y direction, and j = X direction.
		public void printOutGrid()
		{
			Console.WriteLine("The Grid");
			for (int i = 0; i < this._size; i++)
			{
				Console.Write(i + " ..");
				for (int j = 0; j < this._size; j++)
				{
					Console.Write(j + " = " + this._grid[i][j]);
				}
				Console.WriteLine("");
			}
		}
 
		public int returnSize()
		{
			return this._size;
		}
 
		// insert a character into the grid at position X, Y and the character 
		public void insertCharIntoGrid(int pX, int pY, char character)
		{
			this._grid[pY][pX] = character;
		}
 
		//  return the grid reference 
		public char[][] returnGrid()
		{
			return this._grid;
		}
 
	}
 
	class MainClass
	{
		public static void Main(string[] args)
		{
			Grid grid = new Grid();
			grid.printOutGrid();
		}
	}
}

And here is the output.

The Grid
0 ..0 = m1 = y2 = p3 = d4 = d5 = y6 = g7 = p8 = m9 = i10 = t
1 ..0 = k1 = c2 = y3 = n4 = i5 = m6 = q7 = f8 = g9 = p10 = j
2 ..0 = o1 = r2 = v3 = q4 = a5 = i6 = y7 = h8 = k9 = y10 = c
3 ..0 = h1 = u2 = f3 = s4 = v5 = r6 = p7 = g8 = h9 = j10 = b
4 ..0 = n1 = j2 = y3 = u4 = v5 = q6 = n7 = b8 = y9 = w10 = g
5 ..0 = g1 = m2 = i3 = x4 = r5 = a6 = e7 = a8 = w9 = i10 = f
6 ..0 = m1 = c2 = c3 = a4 = r5 = y6 = c7 = v8 = o9 = u10 = k
7 ..0 = f1 = e2 = k3 = c4 = n5 = j6 = s7 = t8 = m9 = g10 = j
8 ..0 = l1 = t2 = f3 = e4 = n5 = i6 = q7 = p8 = e9 = t10 = p
9 ..0 = e1 = w2 = n3 = h4 = j5 = r6 = h7 = o8 = b9 = e10 = o
10 ..0 = y1 = x2 = u3 = j4 = n5 = g6 = n7 = h8 = m9 = t10 = a

I use linux and thus mono is my csharp virtual machine setup, but here is a output of the file command in linux which tells me that the wordsearchcsharp.exe if a mono assembly and thus if you ./wordsearchcsharp.exe will goto the mono virtual machine.. it will link/expand to mono wordsearchcsharp.exe on the command line.

file wordsearchcsharp.exe
wordsearchcsharp.exe: PE32 executable for MS Windows (console) Intel 80386 32-bit Mono/.Net assembly