Transcript Web Server Programming

C#
Content
 A Summary on the C# Language
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Variable Declarations in C#
 int x;
 int x = 5;
 string s;
 string s1, s2;
 object o;
 object obj = new object();
 public string name;
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Statements
 Response.Redirect("NewPage.aspx");
 x = y + 5;
 a = b = c = 5;
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Comments
 // This is a comment
 /*
This
is
a
multiline
comment
*/
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Arrays
 string[] course = new string[3];




course[0] = "Web";
course[1] = "Server";
course[2] = "Programming";
int[] arr = new int[5]{1, 2, 3, 4, 5};
int[][] mat = new int[2][3];
mat[1][2] = 5;
int [,] mat = new int[3,4];
mat[2,3] = 5;
char[] delimeters = new char[]{' ', '\r', '\n'};
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Indexed Properties
 // Creating arrays:
 int[] arr = new int[100];
 int[,] mat = new int[50, 100];
 // Accessing array elements:
 int x = arr[2];
 arr[0] = 5;
 string name = Request.QueryString["name"];
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Properties
 private string m_Username;
public string Username {
get {
return m_Username;
}
set {
m_Username = value;
}
}
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Properties
 public string Name {
get {
return TextBox1.Text;
}
set {
if (value.StartsWith("m")) {
TextBox1.Text = value;
}
}
}
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Automatic Properties
 public string Username {get; set;}
 A private variable to hold the value of the property is
automatically created by the compiler
 It can be used after C# 3.0
 You can create this type of properties in Visual Studio
by typing prop and pressing TAB key two times
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Why Properties?
 Allows read-only and write-only fields
 Can validate a field when it is assigned
 Interface and implementation of data my differ (i.e.,
value can be written into a Label control)
 Visual Studio IDE can list properties of an object when
dot-key is pressed (intellisense)
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Enumerations
 // Declare the enumeration:
public enum MessageSize {
Small = 0, Medium = 1, Large = 2
}
 // Create a field or property:
MessageSize msgSize;
 // Assign a value:
msgSize = MessageSize.Medium;
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Declaring and Calling Methods
 private int Add(int a, int b) {
return a + b;
}
 public void PrintHeader() {
Console.WriteLine("This is a header");
}
 int z = Add(x, y);
 PrintHeader();
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If Statement
 if (a == 3)
TextBox1.Text = "three";
 if (a == 3)
{
TextBox1.Text = "three";
Label1.Text = "four";
}
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If, Else, Else If
 if (a == 1)
Label1.Text = "one";
else if (a == 2)
Label1.Text = "two";
else
Label1.Text = "other";
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Case Statement
 int num = 5;
switch (num) {
case 1:
Label1.Text = "one";
break;
case 2:
case 3:
Label1.Text = "two or three";
break;
default:
Label1.Text = "other";
break;
}
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Case Statement
 string color = "blue";
 switch (color) {
case "red":
Label1.Text = "Red";
break;
case "blue":
Label1.Text = "Blue";
break;
default:
Label1.Text = "Not Red Nor Blue";
break;
}
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Case Statement
 enum MessageSize {Small, Medium, Large};
 MessageSize msgSize = MessageSize.Small;
 switch (msgSize) {
case MessageSize.Small: Label1.Text = "S";
break;
case MessageSize.Medium: Label1.Text = "M";
break;
case MessageSize.Large: Label1.Text = "L";
break;
default: Label1.Text = "---";
break;
}
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For Loop
 for (int i = 0; i < 10; i++)
single_statement();
 for (int i = 0; j < 10; k %= 2) {
statement1();
statement2();
}
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Foreach Loop
 int[] arr = new int[]{5, 7, 9, 10, 3};
 foreach (int number in arr)
{
Label1.Text += number.ToString() + "<br/>";
}
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While Loop
 int n = 5;
 while (n > 0)
{
Label1.Text += n.ToString() + "\r\n";
n--;
}
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Do..While Loop
 int grade = 0;
do
{
grade += DoNextHomework();
} while (grade < 100);
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Exception Handling
 try {
// Code that throws exception
} catch (OverflowException e) {
// Catch a specific exception
} catch (Exception e) {
// Catch the generic exceptions
} finally {
// Execute some cleanup code
}
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String Operations
 string s1 = "Web";
 string s2 = "Programming";
 string s3 = s1 + " " + s2;
 s3 += " (Server Side)";
 // Use StringBuilder class for performance:
StringBuilder s3 = new StringBuilder();
s3.Append("Web");
s3.Append(" Programming");
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Type Casting and Conversion
 double d = 5.4321;
 int n = (int)d;
 string s = n.ToString();
 int n = int.Parse("54321");
 double d = double.Parse("54.321");
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