为什么局部变量必须具有初始值? [英] Why must local variables have initial values?

问题描述

为什么必须在方法内部初始化变量?

Why must I initialize variables inside methods?

int test1; // Not initialized, but OK

public int Foo()
{
   int test2;                 // Not initialized

   int test3 = test1;         // OK
   int test4 = test2;         // An error
}

推荐答案

字段会自动初始化为该类型的逻辑零；这是隐式的.变量必须服从确定分配"，因此必须先分配 才能读取它们.

Fields are automatically initialized to the logical zero for the type; this is implicit. Variables must obey "definite assignment", so must be assigned before they can be read.

ECMA 334v4

ECMA 334v4

第17.4.4节字段初始化

§17.4.4 Field initialization

字段的初始值，是否它可以是静态字段或实例字段，是默认值(§12.2)字段的类型.这不可能观察一个字段的值之前这个默认的初始化有发生，因此永远不会有一个领域未初始化".

The initial value of a field, whether it be a static field or an instance field, is the default value (§12.2) of the field’s type. It is not possible to observe the value of a field before this default initialization has occurred, and a field is thus never "uninitialized".

和

§12.变量

...必须在变量之前明确分配一个变量(第12.3节)可以获得价值....

... A variable shall be definitely assigned (§12.3) before its value can be obtained. ...

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