error: 'NULL' undeclared

Question

File null.c.

int main() { void *p = NULL; return 0; }

I collect using gcc.

 $ gcc null.c

I get an error.

null.c: In function 'main':
null.c: 2: error: 'NULL' undeclared (first use in this function)

What's wrong?

Nicolas Chabanovsky ♦ Nicolas Chabanovsky 38.2k 54 221 438 · Accepted Answer · 2010-11-11T16:39:40

NULL is not a keyword. This is a macro defined in standard headers. To use it you need to connect them.

 #include <stddef.h>

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