变量

Variables 变量

原文：https://go.dev/ref/spec#Variables

A variable is a storage location for holding a value. The set of permissible values is determined by the variable’s type.

​ 变量是用于保存值的存储位置。允许值的集合是由变量的类型决定的。

A variable declaration or, for function parameters and results, the signature of a function declaration or function literal reserves storage for a named variable. Calling the built-in function new or taking the address of a composite literal allocates storage for a variable at run time. Such an anonymous variable is referred to via a (possibly implicit) pointer indirection.

​ 变量声明 、函数参数和结果、函数声明或函数字面量的签名为指定的变量保留存储空间。调用内置函数new或获取复合字面量的地址会在运行时为变量分配存储空间。这样的匿名变量是通过(可能是隐式的)指针间接引用的。

Structured variables of array, slice, and struct types have elements and fields that may be addressed individually. Each such element acts like a variable.

​ 数组、切片和结构体等类型的结构化变量具有可以被单独寻址的元素和字段。每个这样的元素都像一个变量。

个人注释

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package main import "fmt" type St struct { Name string Age int } func main() { var arr = [...]int{1, 2, 3} fmt.Println(&arr[0]) // 0xc000010120 fmt.Println(&arr[1]) //0xc000010128 fmt.Println(&arr[2]) //0xc000010130 var sli = []int{1, 2, 3} fmt.Println(&sli[0]) //0xc000010138 fmt.Println(&sli[1]) //0xc000010140 fmt.Println(&sli[2]) //0xc000010148 var st1 = St{"zlongx", 32} fmt.Println(&st1.Name) //0xc000008078 fmt.Println(&st1.Age) //0xc000008088 }

The static type (or just type) of a variable is the type given in its declaration, the type provided in the new call or composite literal, or the type of an element of a structured variable. Variables of interface type also have a distinct dynamic type, which is the (non-interface) type of the value assigned to the variable at run time (unless the value is the predeclared identifier nil, which has no type). The dynamic type may vary during execution but values stored in interface variables are always assignable to the static type of the variable.

​ 变量的静态类型（或简称为类型）是在其声明中指定的类型、在new调用或复合字面量中提供的类型、或是结构化变量的元素的类型。接口类型的变量还具有独特的动态类型，它是在运行时分配给变量的值的（非接口）类型（除非该值是预先声明的标识符nil，它没有类型）。在执行过程中，动态类型可能会发生变化，但是存储在接口变量中的值始终可以赋给变量的静态类型。

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var x interface{}  // x is nil and has static type interface{}  => x 为 nil，具有静态类型 interface{}
var v *T           // v has value nil, static type *T =>  v 具有值 nil，静态类型 * T
x = 42             // x has value 42 and dynamic type int =>  x 具有值42，动态类型 int
x = v              // x has value (*T)(nil) and dynamic type *T => x 具有值(* T)(nil)和动态类型 * T

A variable’s value is retrieved by referring to the variable in an expression; it is the most recent value assigned to the variable. If a variable has not yet been assigned a value, its value is the zero value for its type.

​ 变量的值是通过在表达式中引用该变量来检索的；它是最近分配给该变量的值。如果一个变量还没有被赋值，它的值就是其类型的零值。