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What is a null pointer?

By admin on Jan 9, 2007 in C Interview Questions, Technical

There are times when it’s necessary to have a pointer that doesn’t point to anything. The macro NULL, defined in , has a value that’s guaranteed to be different from any valid pointer. NULL is a literal zero, possibly cast to void* or char*. Some people, notably C++ programmers, prefer to use 0 rather than NULL.

The null pointer is used in three ways:

1) To stop indirection in a recursive data structure

2) As an error value

3) As a sentinel value

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