golang获取变量或对象类型的几种方式总结

fmt Printf( "%T ")方式示例： var1 := "hello world " fmt Printf( "var1 = %T n ", var1) 这个是

fmt.Printf("%T")方式

示例：

var1 := "hello world"
fmt.Printf("var1 = %T\n", var1)

这个是最简单，也是最推荐的在at rumtime时获取变量类型的方式，

用fmt.Printf("%T")实现返回变量类型的函数

由此衍生出可复用获取变量或者对象type的函数，如下面函数，直接返回变量类型

func typeofVariable(variable interface{}) string {
   return fmt.Sprintf("%T", variable)
}

reflect.TypeOf方式

示例：

var1 := "hello world"
fmt.Printf("var1: %s\n", reflect.TypeOf(var1))

用 reflect包里的函数 TypeOf()来实现，用起来相对来说复杂些，如果只是单纯地想在runtime时获取一下变量类型，还是推荐第一种方式

用reflect.TypeOf实现返回变量类型的函数

由此衍生出可复用获取变量或对象type的函数，如下面函数，直接返回变量类型

func typeofVariable(variable interface{}) string {
    return reflect.TypeOf(variable).String()
}

reflect.ValueOf.Kind()方式

示例：

var1 := "hello world"
fmt.Println(reflect.ValueOf(var1).Kind())

用 reflect.ValueOf.Kind()实现返回变量类型的函数

func typeofVariable(variable interface{}) string {
        return reflect.ValueOf(variable).Kind().String()
}

断言方式

func typeofObject(variable interface{}) string {
        switch variable.(type) {
        case string:
                return "string"
        case int:
                return "int"
        case float32:
                return "float32"
        case float64:
                return "float64"
        case bool:
                return "boolean"
        case []string:
                return "[]string"
        case complex128:
                return "complex128"
        case complex64:
                return "complex64"
        case map[string]float64:
                return "map"
        case Employee:
                return "Employee"
        default:
                return "unknown"
        }
}

代码示例：

package main
 
import (
    "fmt"
    "reflect"
)
 
 
type Employee struct {
    name string
    age  int
    salary float64
}
 
 
// 4 ways to return a variable's type at runtime
 
func typeofObject(variable interface{}) string {
        switch variable.(type) {
        case string:
                return "string"
        case int:
                return "int"
        case float32:
                return "float32"
        case float64:
                return "float64"
        case bool:
                return "boolean"
        case []string:
                return "[]string"
        case complex128:
                return "complex128"
        case complex64:
                return "complex64"
        case map[string]float64:
                return "map"
        case Employee:
                return "Employee"
        default:
                return "unknown"
        }
}
 
func main() {
 
    var1 := "hello world"
    var2 := 10
    var3 := 2.55
    var4 := []string{"BeiJing", "ShangHai", "ShenZhen"}
    var5 := map[string]float64{"BeiJing": 3.2, "ShaiHai": 1.2}
    var6 := complex(3,4)
    var7 := true
    var8 := Employee{"Sam",30,15000.5}
 
    fmt.Println("###############    Using %T with Printf    ########################")
 
    fmt.Printf("var1 = %T\n", var1)
    fmt.Printf("var2 = %T\n", var2)
    fmt.Printf("var3 = %T\n", var3)
    fmt.Printf("var4 = %T\n", var4)
    fmt.Printf("var5 = %T\n", var5)
    fmt.Printf("var6 = %T\n", var6)
    fmt.Printf("var7 = %T\n", var7)
    fmt.Printf("var8 = %T\n", var8)
 
 
    fmt.Println("###############Using reflect.TypeOf Function #######################")
    fmt.Printf("var1: %s\n", reflect.TypeOf(var1))
    fmt.Printf("var2: %s\n", reflect.TypeOf(var2))
    fmt.Printf("var3: %s\n", reflect.TypeOf(var3))
    fmt.Printf("var4: %s\n", reflect.TypeOf(var4))
    fmt.Printf("var5: %s\n", reflect.TypeOf(var5))
    fmt.Printf("var6: %s\n", reflect.TypeOf(var6))
    fmt.Printf("var7: %s\n", reflect.TypeOf(var7))
    fmt.Printf("var8: %s\n", reflect.TypeOf(var8))
 
 
    fmt.Println("###############Using reflect.ValueOf.Kind() ########################")
    fmt.Println(reflect.ValueOf(var1).Kind())
    fmt.Println(reflect.ValueOf(var2).Kind())
    fmt.Println(reflect.ValueOf(var3).Kind())
    fmt.Println(reflect.ValueOf(var4).Kind())
    fmt.Println(reflect.ValueOf(var5).Kind())
    fmt.Println(reflect.ValueOf(var6).Kind())
    fmt.Println(reflect.ValueOf(var7).Kind())
    fmt.Println(reflect.ValueOf(var8).Kind())
 
 fmt.Println("################## Using Type assertions ###########################")
    fmt.Println(typeofObject(var1))
    fmt.Println(typeofObject(var2))
    fmt.Println(typeofObject(var3))
    fmt.Println(typeofObject(var4))
    fmt.Println(typeofObject(var5))
    fmt.Println(typeofObject(var6))
    fmt.Println(typeofObject(var7))
    fmt.Println(typeofObject(var8))
 
 
}
 
/*
几个复用的函数来判断变量的类型at runtime
// Using %T
func typeofVariable(variable interface{}) string {
   return fmt.Sprintf("%T", variable)
}
// Using reflect.TypeOf()
func typeofVariable(variable interface{}) string {
    return reflect.TypeOf(variable).String()
}
// Using reflect.ValueOf().Kind()
func typeofVariable(variable interface{}) string {
        return reflect.ValueOf(variable).Kind().String()
}
*/