Warning C memset

Question

This is my warning.

warning: passing argument 2 of ‘memset’ makes integer from pointer without a cast

Then I changed as follows (make NULL equal to 0)

Before Change : memset(key, NULL, KEY_BYTES);
After Change : memset(key, 0, KEY_BYTES);

Warning deleted.

I am using the linux compiler and gcc, C.

This is the right action.

Answer 1

Depending on the implementation, the C standard library sometimes defines NULL as a null integer (which avoids the warning you saw), but sometimes defines NULL as a null value in a void pointer. The last implementation raises the warning you saw.

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http://en.wikipedia.org/wiki/Stdlib.h:

NULL

stdlib.h stddef.h NULL, , .

NULL , int zero, int zero , * :

#define NULL 0
#define NULL 0L
#define NULL ((void *) 0)

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Answer 2

, NULL ((void *) 0). , - memset , .

Answer 3

memset int. NULL - C. :

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T *p = NULL;
T *q = 0;

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if (p) ...
if (p != NULL) ...
if (p != 0) ...

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int i = 0;
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Answer 4

, . NULL NULL ( #define NULL 0), memset int, , 0, , int.

Answer 5

memset , - . NULL, , C. . 0 .

Answer 6

memset(key, NULL, KEY_BYTES); NULL is the (void*)0 {ie; void* typecasted of int zero}. and the memset 2nd argument should be of type "unsigned int" .

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