C# week8_3

17/03/2010


 
Collection

1. Arraylist
   
2. Hashtable
   
3. Stack
   
4. Que
   

 
Arraylist & foreach

Arraylist al = new Arraylist();

al.Add( ab);

// class of object can be stored

 

string[] s = {"1", "2", "3"}

foreach(string k in s)

{

}

It will work.


 

ABC ab = new ABC();

Arraylist al = new Arraylist();

al.Add(1); //int

al.Add("2"); //string

al.Add(ab); //object of the class

foreach can't use, because datatype of this array is different.


 
IEnumerator

Arraylist al = new Arraylist();

al.Add(5);

al.Add("123");

al.Add(ab);

 

int k = (int)5;

string k1 = (string)123;

ABC k2 = (ABC)ab;

//object o = ab;

//object o1 =new ABC();

//Parent can refer child

 

casting

A a = new B();

B b = (B)a;

 

IEnumerator ie = new IEnumerator();

 

while(ie.Movenext())

{ ---------------- 2roles

1. True or Flase?

2. i++

 

ie.current.Tostring();

}

 

ADO.NET

1. Data provider
   
2. 
   
   
   ADO.NET OBJECT
   
   1. SQL connection
      
   2. SQL command
      
   3. SQL data reader
      
   4. SQL data adaptor
      
   
   
   

Pros.

• 
  
  
  We can use any data source, either file, access, excel or data base.
  
  
  
  

1. 
   
   
   SQL connection
   
   SqlConnection conn = new SqlConnection
   
   (
   
   "Data source = path;
   
   Initial catalogue = data base name;
   
   Integrated security = SSPI"
   
   );
   
   
   
2. 
   
   
   SQL command
   
   SqlCommand cmd = new SqlCommand(" ", con);
   
   
   
3. 
   
   
   SQL datareader
   
   SqlDataReader rdr = cmd.Executereader.
   
   
   
   while(rdr.Read()) //true or false, read row 1
   
   {
   
   int id = rdr["ID"];
   
   string name = rdr["name"];
   
   Conseole.WriteLine(id+name);
   
   }
   
   
   
   rdr.Close();
   
   cmd.Close();
   
   
   
   cmd.ExcecuteNonQuery();//rdr don't use
   
   int i = (int)cmd.ExcecuteScaler();//How many rows?