Go data types (II) overview of data types supported by go and Boolean types

Go Supported data types

Go The language has built-in support for these basic data types ：

• Boolean type ：bool
• integer ：int8、byte、int16、int、uint、uintptr etc.
• Floating point type ：float32、float64
• Plural type ：complex64、complex128
• character string ：string
• Character type ：rune
• Wrong type ：error

Besides ,Go The language also supports the following composite types ：

• The pointer （pointer）
• Array （array）
• section （slice）
• Dictionaries （map）
• passageway （chan）
• Structure （struct）
• Interface （interface）

Unlike other static languages ,Go Added a new channel type , This type is mainly used for communication between different coroutines during concurrent programming , Later on Go Language concurrent programming will be introduced in detail .

Structs are similar to classes in object-oriented programming languages （class）,Go Continue to use C This compound type of language , Instead of introducing a separate class concept like traditional object-oriented programming ,Go The language also presents interfaces as a single type , Later on Go The use of these two types will be introduced in detail during object-oriented programming .

Boolean type

Go The Boolean types in this language are similar to those in other mainstream programming languages , Type keyword is  bool, Can be assigned and can only be assigned to predefined constants  true  and  false. The sample code is as follows ：

var v1 bool 
v1 = true 
v2 := (1 == 2) // v2  It will also be deduced as  bool  type 

Go It's a strongly typed language , Once the variable type is determined , You cannot assign values of other types to this variable , therefore , Boolean types cannot accept assignments of other types , Automatic or forced type conversions are not supported . The following examples are some of the wrong uses , Causes a compilation error ：

var b bool 
b = 1 //  Compile error  
b = bool(1) //  Compile error 

However, the boolean result calculated by the expression can be assigned to Go Boolean type variable ：

var b bool 
b = (1!=0) //  Compile correctly  
fmt.Println("Result:", b) //  The result is Result: true

Besides , Due to strong typing ,Go When a language judges whether a Boolean value is true or false , There are strict restrictions on the types of values , stay PHP In this weakly typed language , The following values are used in Boolean judgment （ Use non strict  ==  Comparison symbol ） Will be considered as  false（JavaScript、Python Also similar ）：

• Boolean value  FALSE  In itself
• integer  0（ zero ）
• Floating point value  0.0（ zero ）
• An empty string , And strings “0”
• An array that does not include any elements
• Special type NULL（ Include variables that have not been assigned ）
• Generated from empty tags SimpleXML object

And in the Go Not in language , Values of different types cannot be used  ==  or  !=  Operator to compare , Errors will be reported at compile time , For example, the following code ：

b := (false == 0);

The following errors will be reported during compilation ：

annot convert 0 (type untyped number) to type bool
invalid operation: false == 0 (mismatched types bool and int)

Again ,!  Operators also cannot act on non Boolean values .