Learn notes from scratch (day 49)--Extended statement

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The syntax format for declaring an extension is as follows:

extensiontype name {   

    // add new features

}

the keyword that declares the extension isextension, the "type name" isSwift, including classes, structs, and enumerations, but we can still extend basic data types such as Integer, Float, Boolean, string, and so on, because these types are inherently struct-type. OpenIntis defined as follows:

struct Int:signedinteger {    init ()    init (_ Value:int)    static func convertfromintegerliteral (Value:int)-& Gt int    Typealias arrayboundtype = int    func getarrayboundvalue (), int    static var max:int {get}    static var min:int {get}}

visible from DefinitionIntis a struct type. is not onlyInttypes, the type of data that we are familiar with, such as Integer, Float, Boolean, string, and so on, is essentially struct-type.

Swift The new features in the extension mechanism that can be added in the original type include:

• Instance calculation properties and type calculation properties

• Instance methods and Type methods

• Subscript

Content such as nested types can also be extended, and extensions can also comply with protocols.

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Learn notes from scratch (day 49)--Extended statement