C# 基础(更新中)

Data Structure#

There're two types of variables in C#, reference type and value type.
Enum:

enum Color{
Red=0,
Green=1
}

//equals to 
enum Color{
Red,//start from 0 as default
Green
}

int to enum:(Color)val

Arrays and Collections#

Array#

declare array:

new int[10]
new int[10]{xx,xx.....};
new int[]{aa,aa};

Collection#

List<string> theList=new List<string>();//can use value type here, not only reference type
theList.Count;//size of the list

class#

when calling same name class with different namespace, it will use class of same namespace first, then System namespace.

fields and properties#

1. can't use var to declare fields like var count=0,must use int count=0
2. const is static, so we can't use them together like public static const int count=0
3. rules of naming fields and property: first letter with uppercase is public, first letter with lowercase is private.

Auto-implemented property: remove their private fields.
initiate with default: public MyClass val {get;set;} = new MyClass();

anonymous type#

for the cases:

• only use in one function and not need for other functions
• only exists for only short time, and will be stored to other places

var val=new {name='Alex', age=12};

Extensions#

class TheExtensionClass{
    public int toInt(this string value){
        return int.Parse(value);
    }
}

//so that the function can be called on string
str.toInt();

function#

out, in and ref#

if use out/in/ref for value type variable, then it will convert to reference type.
must initiate out variable in the function before use it.

default parameter and named parameter#

Default parameter

• must declared after non-default parameter
• if we don't want to give value to the first default parameter but want to give the second default parameter, we can't do this without named parameter

Named parameter:
can call the function and break the sequence of parameters, especially for default parameter

special function:lambda#

for the cases:

• short function

var res=theList.Find(MyFunc);
boolean MyFunc(Student aStudent){
    return studentName="abc";
}

theList.Find(student=>{
    return studentName="abc";
});

theList.Find(student=> studentName="abc");

Event and asynchronous programming#

Event#

for the cases:
when executing monitor function, it will automatically execute the monitored function

1. declare Action variable in class A:Action action
2. binding the action variable to f2 (monitored function) of class B:action+=f2
3. trigger the event: in f3(monitor function) call the action with action();
   ### asynchronous programming
   like event
   RequestSupport(CallBackFunc)

Exception and log#

Exception#

try{
}catch{
}
try{
}catch(FormatException){
}
try{
}catch(FormatException e){
    print e;
    print e.Message;
}

Log#