2015-10-27 c#3

Three. String Patchwork StringBuilder

StringBuilder sb= New StringBuilder ();

Sb.append ("AAA");

Sb.append ("bbbb");

Console.WriteLine (Sb.tostring ());

Four. Traverse

string [] astring={"AAA", "BBB", "CCCC", "dddd"};

foreach (Var a in astring)

{

Console.WriteLine (c);

}

Five. Error, exception

The 5.1 error is a grammatical problem and cannot be compiled.

Exceptions can be compiled but not run correctly.

5.2 Resolving exceptions

Try

{The code to which the exception occurred

}

catch (Exception type, exception object name)

{The code being processed

}

Finaly

{The code to execute regardless of whether an exception occurred

}

Try
{
String[] astring = {"AAA", "CCC", "dddd", "eeeeee"};
Console.WriteLine (Astring[5]);
}
catch (Exception ex)
{
Console.WriteLine (ex. message);//Print out exception information

Console.WriteLine ("The website is under repair ...");
}

----------------Array

I. One-dimensional arrays

Disclaimer: int[] a={1,2,3}//Common

Int[] A=new int[3]; a[0]=1;a[1]=2;

Int[] a =new int[3]{1,2,3}; [3] 3 of the inside can be omitted

Two. Two-dimensional array

Statement: int[,]a={{1,2},{2,3},{3,4}};

Int[,]a=new int[3,2];a[0,0]=1;//a Row One column 1

int[,] i = new int[3,2] {{1, 2}, {1, 1}, {2, 3}};//[3,2] The array cannot be saved

Three. Adding and removing array elements (arrylist)

3.1 is a collection that is used to store data, to import the System.Collections namespace when used

The size of the arrylist can be dynamically increased as required

3.2 object is the parent class of any data type

int[] i = new int[] {1, 2, 3, 4};

ArrayList List = new ArrayList ();

foreach (Var a in i)

{

List.add (a);//Add A to List

}

List.removeat (0);//Delete First element

List.add (0);//Add 0 at the end of the list

List.insert (1, 5);//Insert 5 at index value 1

List.clear ();//Clear all existing elements

foreach (var b in List)

{

Console.Write (b);

}

The generic form of 3.3 ArrayList list<t>

int [] anumber={2,23,23,45,67,5,2}

List<int> list=new list<int> ();

foreach (Var a in anumber)

{

List. Add (a);

}

3.4 Hashtable

Hashtable ht = new Hashtable ();
Ht. ADD ("Key1", "AAAA");
Ht. ADD ("Key2", "CCCC");
foreach (Var key in Ht. Keys)
{
Console.WriteLine (Ht[key]);
}

The generic form of 3.5 hashtable dictionary

Traversal of Dictrionary

dictionary<string, string> dt = new dictionary<string, string> ();
Dt. ADD ("Key1", "daaa");
Dt. ADD ("Key2", "ddddd");
foreach (var key in dt.) Keys)
{
Console.WriteLine (Dt[key]);
}

Four. Encapsulation

Public all files in the current namespace can be called across assemblies (another new class library created) for all files

Protect internal all the files under the current namespace, as well as the cross-assembly subclasses inside

Internal all the files under the current namespace. (For a class, the default access modifier is internal)

Protect in this class or its subclasses, or in subclasses of a cross-assembly

Private can only be used within this class. (variable, method default access modifier is private)

2015-10-27 c#3