Go learning notes (2) basic types and statements (1)

This section is about go Basic types and declarations of ,go On the whole, the basic types of are not much different from other languages , but go The basic types of languages also have their own characteristics .

Built in type

Zero value

go All variables that are defined but not assigned a value will be assigned a zero value , Each type has its own zero value .

Literal

go There are five literal quantities , Include common integers 、 Floating point numbers 、 character 、 Strings and less common complex numeric facets .

The whole number area

There are the following kinds of integer face quantities ：

• 0b It starts with binary numbers

  fmt.Println(0b111) //  Output 7 
  

• 0o It starts with an octal number

  fmt.Println(0o11) //  Output 9
  

• 0x It starts with a hexadecimal number

  fmt.Println(0xff) //  Output 255
  

• What has no prefix is decimal number

  fmt.Println(22) //  Output 22
  

For long strings of numbers go It is allowed to underline numbers

fmt.Println(1_234_5_6_789) // Output 123456789

Floating point face count

Floating point number facets are similar to integer number facets

fmt.Println(1.2345) // Output 1.2345

It can be used e To represent scientific notation 10 The power of

fmt.Println(1.2345e2) // Output 123.45

Hexadecimal floating-point number facets are troublesome to interpret , Just look at the examples ：
0xa.bpc Represents a hexadecimal number a.b ride 2^c,p It's similar to the above e, Express 2 The power of .

0x1p-2     // == 1.0/4 == 0.25
0x2.p10    // == 2.0 * 1024 == 2048.0
0xap0 // == 10*1 == 10
0x0.1p0 // == 1/16*1 == 0.0625

Similarly, underscores can also be used in floating-point numbers

fmt.Println(1.23_45) //  Output 1.2345

Rune （rune） Literal

stay go Through... In language rune Literal quantity can realize the representation of various characters , Actually, one. rune Literal quantity is a int32 Type of number .rune Literal quantity can use single quotation marks '' Cover up .

Use fmt.Println() Print rune The numeric value of literal quantity will be printed by default , If you want to print out the characters it represents, you need to convert them into string type

fmt.Println('a') //  Output 97
fmt.Println(string('\u0061')) //  Output a
fmt.Println(string(128514)) //  Output 

Literal of a string

stay go There are two languages , One is to use double quotation marks "" The enclosed , Another is to use backquotes `` The enclosed .

String literals enclosed in double quotation marks are basically similar to those in other languages .

fmt.Println(" Notes on Jiangda ") //  Output Jiangda notes 

Use back quotes `` The enclosed string can contain any character except backquotes .

This makes it very suitable for quoting large paragraphs of text without worrying about line breaks and indentations , Strings quoted in backquotes are saved intact .

fmt.Println(`----
 Big is not much   Haina river 
 There is no limit to learning   Between heaven and earth `)
// Here is the output ：
//----
// Big is not much   Haina river 
// There is no limit to learning   Between heaven and earth 

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Welcome to my WeChat official account. Notes on Jiangda