全局变量是否会自动初始化为0？

OwnWaterloo

与C标准无关
beepbug 发表于 2010-07-31 17:41

c99 6.7.8-10
If an object that has automatic storage duration is not initialized explicitly, its value is
indeterminate. If an object that has static storage duration is not initialized explicitly,
then:
— if it has pointer type, it is initialized to a null pointer;
— if it has arithmetic type, it is initialized to (positive or unsigned) zero;
— if it is an aggregate, every member is initialized (recursively) according to these rules;
— if it is a union, the first named member is initialized (recursively) according to these rules.

c89 6.5.7
If an object that has automatic storage duration is not initialized explicitly. its value is
indetelminate.74) If an object that has static storage duration is not initialized explicitly. it is
initialized implicitly as if every member that has arithmetic type were assigned 0 and every
member that has pointer type were assigned a null pointer constant.

74 Unlike in the base document. any automatic duration object may be initialized

beepbug

这个，你得先弄清楚UNIX与C的关系，就不会理解偏了。

jeasun

同意6樓的，初始化全局變量會增大可執行文件的大小，
沒有好處

caboy_cu

肯定清零，规范里有

而且可以省rom