golang : difference between var b Buffer and bytes. 缓冲区{}

Question

var b bytes.Buffer // A Buffer needs no initialization.


b := bytes.Buffer{}

这两个有什么区别？我在这里试过:http://play.golang.org/p/lnkkULeIYm没看出区别。谢谢，

Answer 1

:= 是 var 的简写语法，在这种情况下 b 是一个零值 bytes.Buffer。

var b bytes.Buffer // is the same as
var b = bytes.Buffer{} // is the same as 
b := bytes.Buffer{}

您不能在函数外使用简写版本，因此对于全局变量，您必须使用 var。

来自 http://tip.golang.org/ref/spec#Short_variable_declarations :

Unlike regular variable declarations, a short variable declaration may redeclare variables provided they were originally declared earlier in the same block with the same type, and at least one of the non-blank variables is new.

As a consequence, redeclaration can only appear in a multi-variable short declaration. Redeclaration does not introduce a new variable; it just assigns a new value to the original.