Go-Type

在谈论struct和interface已经用到了type这个关键字。

另外，Go的type另外一种常用功能，是类似于C/C++的typedef。在Go的package中，这种用法非常常见。

A type declaration defines a new named type that has the same underlying type as an existing type. The named type provides a way to separate different and perhaps incompatible uses of the underlying type so that they can’t be mixed unintentionally.

type name underlying-type 

示例：

package main import ( "fmt" ) type Hello interface { out() } type MyInt int func (myInt *MyInt) out() { fmt.Println("MyInt.out():", *myInt) } func foo(i MyInt) { fmt.Println("foo():", i) } func main() { var i MyInt i = 5 i.out() //MyInt.out(): 5 foo(i) // foo(): 5 foo(1) // foo(): 1 var x int x = 100 //foo(x) //cannot use x (type int) as type MyInt in argument to foo foo(MyInt(x)) // foo(): 100 } 

注：foo(MyInt(x)) 给出了Go中强制类型转换的使用示例。——和C/C++的类型转换语法刚好相反（e.g. foo((MyInt)x)）。