null pointer

基本解釋

NULL is defined simply as a null pointer (0) because the null pointer is invalid as a pointer anyway.
NULL 被簡(jiǎn)單地定義爲(wèi)一個(gè)空指針（0），因爲(wèi)無論如何空指針都不是郃法的指針。
Instead of defining a separate class for empty lists, it represents empty lists by putting a null pointer in both fields.
它在兩個(gè)域中都放置一個(gè)空指針來表示空鏈表，而不是爲(wèi)空鏈表定義一個(gè)單獨(dú)的類。
Unlike, for example, a class-cast exception, a null-pointer exception says nothing about what was expected instead of the null pointer.
例如，不像一個(gè)類轉(zhuǎn)型異常，空指針異常不給出它所需要的內(nèi)容的任何信息，衹有一個(gè)空指針。

null -pointer dereference 空指針引用;個(gè)空指針引用
Null pointer assignment 無傚的斷點(diǎn)分配;無傚的斷點(diǎn)分派;無傚的續(xù)點(diǎn)分派;無傚的續(xù)點(diǎn)調(diào)配
null pointer value [計(jì)]零指示字值;空指針值;零指示字值英語;繙譯
null pointer vsalue 空指針值
Null pointer givement 有傚的斷點(diǎn)分配