Golang 变量

2018-12-31 10:31:23 Albin Wong 1382

Golang变量声明,变量初始化,变量赋值,匿名变量,常量 const

#### 变量声明
布尔类型： bool  
整型:int8、byte、int16、int、uint、uintptr等 浮点类型:float32、float64  
复数类型:complex64、complex128  
字符串:string  
字符类型:rune  
错误类型:error   
复合类型:   
 - 指针(pointer)  
 - 数组(array)  
 - 切片(slice)  
 - 字典(map)  
 - 通道(chan)  
 - 结构体(struct)  
 - 接口(interface)

```go
    var v1 int // 整型
    var v2 string //字符串
    var v3 [10]int  // 数组
    var v4 []int // 数组切片
    var v5 struct {  // 结构体
        f int 
    }
    var v6 *int  // 指针
    var v7 map[string]int // map,key为string类型， value为int类型
    var v8 func(a int) int // 匿名函数
    var {
        v1 int
        v2 string
    }
```
> 整形值范围

类型 | 长度(字节) | 值范围
--- | --- | ---
int8 | 1 | -128~127
uint8(即byte) | 1 | 0～255
int16 | 2 | -32768～32767
uint16 | 2 | 0～65535
int32 | 4 | -2147483648～2147483647
uint32 | 4 | 0～4294967295
int64 | 8 | 9223372036854775808~9223372036854775807
uint64 | 8 | 0~18446744073709551615
int | 平台相关 | 平台相关
uint | 平台相关 | 平台相关
uintptr | 同指针 | 32位下为4字节 64位下为8字节

#### 变量初始化
```go
    var v1 int = 10
    var v2  = 10
    v3 := 10 //:=左侧的变量不应该是已经被声明过的，否则会导致编译错误
```

#### 变量赋值
var v10 int  
v10 = 123  
> 交换两个变量  
i, j = j, i

获取变量的类型`reflect.TypeOf(var)`

#### 匿名变量
假设GetName()函数的定义如下，它返回3个值，分别为firstName、lastName和 nickName:  
```go
func GetName() (firstName, lastName, nickName string) {
    return "May", "Chan", "Chibi Maruko"
} 
```
若只想获得nickName，则函数调用语句可以用如下方式编写:  
`_, _, nickName := GetName()`

#### 常量 const
常量可以是数值类型(包括整型、
浮点型和复数类型)、布尔类型、字符串类型

*注：==常量赋值可以是一个表达式，由于常量的赋值是一个编译期行为，但不能出现任何需要运行期才能得出结果的表达
式==

(3) Comments

John Doe- Reply

February 26, 2013 at 1:18 pm
- saqib sarwar- Reply
  
  February 26, 2013 at 1:20 pm
  
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John Doe- Reply

February 26, 2013 at 1:27 pm

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Golang 变量

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John Doe- Reply

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