Similar to an undefined external error, except that the reference is via metadata.

与未定义的外部错误类似，不同的是引用是通过元数据。

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Lacking an external focus, the mind turns inward on itself and creates problems to solve, even if the problems are undefined or unimportant.

缺乏外部的兴趣焦点，注意力因此转向内部，引发需要解决的内部问题；尽管这些问题可能很模糊和不重要。

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External and static variables are initialized to zero by default. Automatic variables for which is no explicit initializer have undefined (i. e., garbage) values.

外部变量和静态变量初始的时候默认值为零，自动变量在初始的时候是没有默认值的。

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