see MSDN: --------------- If only one argument is passed to the Array constructor, and the argument is a number, it must be an unsigned 32-bit integer (< approximately four billion). That value then becomes the size of the array--------------- 如果仅用一个参数构造这个数组，且这个参数是一个数字，它必须是一个无符号32位整型（小于大约40亿)，因而这个数字成为这数组的大小
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If only one argument is passed to the Array constructor, and the argument is a number, it must be an unsigned 32-bit integer (< approximately four billion). That value then becomes the size of the array---------------
如果仅用一个参数构造这个数组，且这个参数是一个数字，它必须是一个无符号32位整型（小于大约40亿)，因而这个数字成为这数组的大小