C# Base Classes

LA C#, SIG of LAFox.org

August 6, 2002

Overview

Various base classes will be described Examples showing use and performance of these classes will be presented

Code examples and this presentation are posted on the web page http://www.vi-i.com/talks and on the web site http://www.lacsharp.org.

The fundamental System.Object base class and how its Equals method is used and overridden

All classes are subclasses of System.Object

Methods of System.Object

ToString – string representation (for output display); by default the name of the object

GetHashCode – gets a hash code so object can be looked up in a dictionary (integer value)

Equals – returns .T. if current object’s “value” matches value object; used to find objects in collections

ReferenceEquals – returns .T. if object is the same as argument object (exactly the same object; not just the same value)

GetType – returns the type of the object in System.Type

MemberwiseClone – copies to another object all data values

String Handling, string builder, and how strings are concatenated

Basic String Methods:

int.CompareTo(string2) [uses locale to distinguish chars]

int=string1.CompareOrdinal(string2) [no locale used]

int=string1.IndexOf(char), int=string1.IndexOf(substring)

int=string1.IndexOfAny(char[])

int=string1.LastIndexOf(char), int=string1.LastIndexOf(substring)

int=string1.LastIndexOfAny(char[])

string=string1.PadLeft(int), string=string1.PadLeft(int,char)

string=string1.PadRight(int), string=string1.PadRight(int,char)

string=string1.Replace(substring1,substring2)

string[]=string1.Split(char) – split where char occurs into substrings

string=string1.Substring(int offset,int length) [offset=0,1,…]

string=string1.ToLower(), string=string1.ToUpper(), string=string1.Trim()

String Handling, continued

StringBuilder – preallocates memory and appends string segments into that memory, much faster than repeated use of string=string+newString

/* build string representing contents of a string[] array */

private string ArrayToString(string[] array)

{

StringBuilder Output=new StringBuilder(1000);

int i;

if (array.Length==0) return "";

for (i=0;i<array.Length;i++)

Output.Append("\",\""+array[i].ToString());

return "("+Output.ToString().Substring(2)+"\")";

}

Formatting values into strings:

String.Format("Format {0,10:E} and {0,8:F} of pi and e:", System.Math.PI,

System.Math.E);

Regular Expressions - classes and methods for implementing fast, complex string searches

Search text in richTextBox1 on form using regular expression in textBox1,

and show result by highlighting matches in bold font:

MatchCollection Matches=Regex.Matches(richTextBox1.Text,

textBox1.Text, RegexOptions.IgnoreCase |

RegexOptions.IgnorePatternWhitespace |

RegexOptions.ExplicitCapture);

System.Drawing.Font currentFont = richTextBox1.SelectionFont;

System.Drawing.FontStyle newFontStyle;

newFontStyle = FontStyle.Bold;

foreach (Match NextMatch in Matches)

{

this.richTextBox1.SelectionStart=NextMatch.Index;

this.richTextBox1.SelectionLength=NextMatch.ToString().Length;

richTextBox1.SelectionFont = new Font(currentFont.FontFamily,

currentFont.Size, newFontStyle);

};

Groups of Objects - Arrays, Array Lists, Collections, and Dictionaries

Arrays

int[] Array=new int[10000000]; int i; long sum; sum=0;

for (i=0;i<10000000;i++) Array[i]=i+1;

for (i=0;i<10000000;i++) sum=sum+Array[i];

MessageBox.Show("Sum(array[i]=i) from 1 to 1,000,000 = "+

sum.ToString(),"Array",MessageBoxButtons.OK,

MessageBoxIcon.Information);

ArrayLists

ArrayList List=new ArrayList(100000);

int i; long sum=0;

for (i=0;i<int.Parse(this.textBox2.Text);i++) List.Add(i+1);

MessageBox.Show("Created array list","Created Array List",

MessageBoxButtons.OK, MessageBoxIcon.Information);

for (i=0;i<List.Count;i++) sum=sum+(int)List[i];

MessageBox.Show("Sum(ArrayList) from 1 to "+

List.Count.ToString()+" = "+sum.ToString(),"Summed Array List",

MessageBoxButtons.OK, MessageBoxIcon.Information);

Groups of Objects, continued

Collections

/* Create and sum integer sequence collection */

IntegerSequence Sequence=new IntegerSequence(

int.Parse(textBox3.Text),int.Parse(textBox4.Text));

long sum=0;

foreach (int Integer in Sequence) sum=sum+Integer;

MessageBox.Show("Sum(integer sequence collection) from

"+textBox3.Text.Trim()+" to "+textBox4.Text.Trim()+" = "+sum.ToString(),

"Collection",MessageBoxButtons.OK, MessageBoxIcon.Information);

public class IntegerSequence : IEnumerable

{

public int Start; public int End;

public IntegerSequence(int Start, int End)

{this.Start=Start; this.End=End;}

public IEnumerator GetEnumerator()

{return new SequenceCollection(this);}

}

Groups of Objects: Collection enumerator class

public class SequenceCollection : IEnumerator

{

IntegerSequence sequence; int index;

public SequenceCollection(IntegerSequence Sequence)

{sequence=Sequence; index=sequence.Start-1;}

public bool MoveNext()

{++index; return (index>sequence.End)?false:true;}

public object Current{

get{

   if (index<sequence.Start | index>sequence.End)

      throw new InvalidOperationException(

         "The selected IntegerSequence object is out of range");

   return index;}

}

public void Reset() {index=sequence.Start-1;}

}

Groups of Objects: Dictionaries

Dictionaries

/* Create dictionary of squares and look up and sum entries */

Hashtable Dictionary=new Hashtable(31);

long i;

long sum=0;

int m=int.Parse(this.textBox5.Text);

int n=int.Parse(this.textBox6.Text);

for (i=m;i<=n;i++) Dictionary.Add(i,(i*i));

MessageBox.Show("Created dictionary","Created Dictionary",

MessageBoxButtons.OK,MessageBoxIcon.Information);

for (i=m;i<=n;i++) sum=sum+(long)Dictionary[i];

MessageBox.Show("Sum(dictionary entry = n*n) from "+m.ToString()+

" to "+n.ToString()+" = "+sum.ToString(),"Summed Dictionary",

MessageBoxButtons.OK, MessageBoxIcon.Information);

Reflection - classes that assign attributes to code that can be queried at build and at run time

/* show type and methods of objects obj */

private string ShowType(object obj)

{

Type type=obj.GetType();

StringBuilder Output=new StringBuilder(1000);

Output.Append("Type "+type.Name+" ("+type.FullName+")\nin "+

type.Namespace+"\n");

if (type.BaseType != null)

Output.Append("Base type "+type.BaseType.Name+"\n");

if (type.UnderlyingSystemType != null)

Output.Append(

"Underlying system type "+type.UnderlyingSystemType.Name+"\n");

Output.Append("\nPublic Members:\n");

MemberInfo[] Members=type.GetMembers();

foreach (MemberInfo Member in Members)

Output.Append(Member.DeclaringType+

" "+Member.MemberType+": "+Member.Name +"\n");

return Output.ToString();

}

Reflection, continued

One can also create custom attributes that can be assigned to blocks of code, and methods that will display these attributes (e.g., author, date of last change, version number)

Threading - starting multiple execution threads, prioritorizing and synchronizing

string Title; int form;

void TestThreading {

Title = this.Text; /* from form */

int i; form=0;

/* with threading */

for (i=0; i<n && i<5; i++) {

Threads[i]=new Thread(new ThreadStart(StartWindow));

Threads[i].Start();}

/* without threadng */

for (i=0; i<n && i<5; i++) StartWindow();

}

void StartWindow() {

FormThreading aForm = new FormThreading();

aForm.Text = Title+":"+(form+1).ToString();

Forms[form++] = aForm;

aForm.ShowDialog();

}

Performance of C# vs. VFP and ASP

1,000,000 string concatenations

C#: 190 seconds

C# with StringBuilder: 0.3 seconds

VFP: 3 seconds

ASP 2.0 (not ASP.NET): 7 seconds

Sum i (i=1 to 1,000,000)

C# array: 0.1 seconds (numbers stored)

C# array list: 15 seconds (numbers stored)

C# collection: 0.1 seconds (numbers generated by method calls)

C# dictionary: 4 seconds (numbers stored)

VFP code: 1.2 seconds (calculation; nothing stored)

VFP build cursor and sum it: 4.5 seconds (numbers stored)


	Various base classes will be described Examples showing use and performance of these classes will be presented

	Code examples and this presentation are posted on the web page http://www.vi-i.com/talks and on the web site http://www.lacsharp.org.


	All classes are subclasses of System.Object
	Methods of System.Object
		ToString – string representation (for output display); by default the name of the object
		GetHashCode – gets a hash code so object can be looked up in a dictionary (integer value)
		Equals – returns .T. if current object’s “value” matches value object; used to find objects in collections
		ReferenceEquals – returns .T. if object is the same as argument object (exactly the same object; not just the same value)
		GetType – returns the type of the object in System.Type
		MemberwiseClone – copies to another object all data values


	Basic String Methods:
		int.CompareTo(string2) [uses locale to distinguish chars]
		int=string1.CompareOrdinal(string2) [no locale used]
		int=string1.IndexOf(char), int=string1.IndexOf(substring)
		int=string1.IndexOfAny(char[])
		int=string1.LastIndexOf(char), int=string1.LastIndexOf(substring)
		int=string1.LastIndexOfAny(char[])
		string=string1.PadLeft(int), string=string1.PadLeft(int,char)
		string=string1.PadRight(int), string=string1.PadRight(int,char)
		string=string1.Replace(substring1,substring2)
		string[]=string1.Split(char) – split where char occurs into substrings
		string=string1.Substring(int offset,int length) [offset=0,1,…]
		string=string1.ToLower(), string=string1.ToUpper(), string=string1.Trim()


StringBuilder – preallocates memory and appends string segments into that memory, much faster than repeated use of string=string+newString
		/* build string representing contents of a string[] array */
		private string ArrayToString(string[] array)
		{
		StringBuilder Output=new StringBuilder(1000);
		int i;
		if (array.Length==0) return "";
		for (i=0;i<array.Length;i++)
		Output.Append("\",\""+array[i].ToString());
		return "("+Output.ToString().Substring(2)+"\")";
		}
Formatting values into strings:
	String.Format("Format {0,10:E} and {0,8:F} of pi and e:", System.Math.PI,
	System.Math.E);


	Search text in richTextBox1 on form using regular expression in textBox1,
	and show result by highlighting matches in bold font:

	MatchCollection Matches=Regex.Matches(richTextBox1.Text,
	textBox1.Text, RegexOptions.IgnoreCase \|
	RegexOptions.IgnorePatternWhitespace \|
	RegexOptions.ExplicitCapture);

	System.Drawing.Font currentFont = richTextBox1.SelectionFont;
	System.Drawing.FontStyle newFontStyle;
	newFontStyle = FontStyle.Bold;

	foreach (Match NextMatch in Matches)
	{
	this.richTextBox1.SelectionStart=NextMatch.Index;
	this.richTextBox1.SelectionLength=NextMatch.ToString().Length;
	richTextBox1.SelectionFont = new Font(currentFont.FontFamily,
	currentFont.Size, newFontStyle);
	};


	Arrays

		int[] Array=new int[10000000]; int i; long sum; sum=0;
		for (i=0;i<10000000;i++) Array[i]=i+1;
		for (i=0;i<10000000;i++) sum=sum+Array[i];
		MessageBox.Show("Sum(array[i]=i) from 1 to 1,000,000 = "+
		sum.ToString(),"Array",MessageBoxButtons.OK,
		MessageBoxIcon.Information);

	ArrayLists

		ArrayList List=new ArrayList(100000);
		int i; long sum=0;
		for (i=0;i<int.Parse(this.textBox2.Text);i++) List.Add(i+1);
		MessageBox.Show("Created array list","Created Array List",
		MessageBoxButtons.OK, MessageBoxIcon.Information);
		for (i=0;i<List.Count;i++) sum=sum+(int)List[i];
		MessageBox.Show("Sum(ArrayList) from 1 to "+
		List.Count.ToString()+" = "+sum.ToString(),"Summed Array List",
		MessageBoxButtons.OK, MessageBoxIcon.Information);


	Collections

	/* Create and sum integer sequence collection */
	IntegerSequence Sequence=new IntegerSequence(
	int.Parse(textBox3.Text),int.Parse(textBox4.Text));
	long sum=0;
	foreach (int Integer in Sequence) sum=sum+Integer;
	MessageBox.Show("Sum(integer sequence collection) from
	"+textBox3.Text.Trim()+" to "+textBox4.Text.Trim()+" = "+sum.ToString(),
	"Collection",MessageBoxButtons.OK, MessageBoxIcon.Information);

	public class IntegerSequence : IEnumerable
	{
	public int Start; public int End;
	public IntegerSequence(int Start, int End)
	{this.Start=Start; this.End=End;}
	public IEnumerator GetEnumerator()
	{return new SequenceCollection(this);}
	}


	public class SequenceCollection : IEnumerator
	{
	IntegerSequence sequence; int index;
	public SequenceCollection(IntegerSequence Sequence)
	{sequence=Sequence; index=sequence.Start-1;}
	public bool MoveNext()
	{++index; return (index>sequence.End)?false:true;}
	public object Current{
	get{
	if (index<sequence.Start \| index>sequence.End)
	throw new InvalidOperationException(
	"The selected IntegerSequence object is out of range");
	return index;}
	}
	public void Reset() {index=sequence.Start-1;}
	}


	Dictionaries

	/* Create dictionary of squares and look up and sum entries */
	Hashtable Dictionary=new Hashtable(31);
	long i;
	long sum=0;
	int m=int.Parse(this.textBox5.Text);
	int n=int.Parse(this.textBox6.Text);
	for (i=m;i<=n;i++) Dictionary.Add(i,(i*i));
	MessageBox.Show("Created dictionary","Created Dictionary",
	MessageBoxButtons.OK,MessageBoxIcon.Information);
	for (i=m;i<=n;i++) sum=sum+(long)Dictionary[i];
	MessageBox.Show("Sum(dictionary entry = n*n) from "+m.ToString()+
	" to "+n.ToString()+" = "+sum.ToString(),"Summed Dictionary",
	MessageBoxButtons.OK, MessageBoxIcon.Information);


	/* show type and methods of objects obj */
	private string ShowType(object obj)
	{
	Type type=obj.GetType();
	StringBuilder Output=new StringBuilder(1000);
	Output.Append("Type "+type.Name+" ("+type.FullName+")\nin "+
	type.Namespace+"\n");
	if (type.BaseType != null)
	Output.Append("Base type "+type.BaseType.Name+"\n");
	if (type.UnderlyingSystemType != null)
	Output.Append(
	"Underlying system type "+type.UnderlyingSystemType.Name+"\n");
	Output.Append("\nPublic Members:\n");
	MemberInfo[] Members=type.GetMembers();
	foreach (MemberInfo Member in Members)
	Output.Append(Member.DeclaringType+
	" "+Member.MemberType+": "+Member.Name +"\n");
	return Output.ToString();
	}


	One can also create custom attributes that can be assigned to blocks of code, and methods that will display these attributes (e.g., author, date of last change, version number)


	string Title; int form;

	void TestThreading {
	Title = this.Text; /* from form */
	int i; form=0;
	/* with threading */
	for (i=0; i<n && i<5; i++) {
	Threads[i]=new Thread(new ThreadStart(StartWindow));
	Threads[i].Start();}

	/* without threadng */
	for (i=0; i<n && i<5; i++) StartWindow();
	}

	void StartWindow() {
	FormThreading aForm = new FormThreading();
	aForm.Text = Title+":"+(form+1).ToString();
	Forms[form++] = aForm;
	aForm.ShowDialog();
	}


	1,000,000 string concatenations
			C#: 190 seconds
			C# with StringBuilder: 0.3 seconds
			VFP: 3 seconds
			ASP 2.0 (not ASP.NET): 7 seconds

	Sum i (i=1 to 1,000,000)
			C# array: 0.1 seconds (numbers stored)
			C# array list: 15 seconds (numbers stored)
			C# collection: 0.1 seconds (numbers generated by method calls)
			C# dictionary: 4 seconds (numbers stored)
			VFP code: 1.2 seconds (calculation; nothing stored)
			VFP build cursor and sum it: 4.5 seconds (numbers stored)