gethostbyname C function

**ladesidude** · 07-09-2008

Hi all,

I need to understand this point, so perhaps someone would be able to help. The following code:

Code:

struct hostent {
   138	        char*    h_name;       ;; official name
   139	        char**   h_aliases;    ;; alias list
   140	        int      h_addrtype;   ;; host address type 
   141	        int      h_length;     ;; length of address 
   142	        char**   h_addr_list;  ;; list of addresses 
   143	     };

is part of the C Library. Of this, I am interested in knowing

Code:

char**   h_aliases;

points to an array of strings and uses NULL (or 0) as the last element in the list. If you put, -1 in place of NULL, you get a compiler warning. So my question is, why is the compiler willing to accept an array initialization in which the last element is not a string, but an integer?

Thanks

**Cactus_Hugger** · 07-09-2008

you get a compiler warning .... why is the compiler willing to accept

It isn't willing to accept it, so it gives a warning. How/what exactly are you initializing? (And why?) (code snip?) Usually you're reading a hostent, not writing to one...

Code:

#include <stdio.h>

int main()
{
	char *hosten[] =
		{ "test", "ing", "this", -1};
}

Code:

$ gcc -o oddprog tomfoolery.c
tomfoolery.c: In function `main':
tomfoolery.c:6: warning: initialization makes pointer from integer without a cast

**ladesidude** · 07-09-2008

Originally Posted by Cactus_Hugger

It isn't willing to accept it, so it gives a warning. How/what exactly are you initializing? (And why?) (code snip?) Usually you're reading a hostent, not writing to one...

Code:

#include <stdio.h>

int main()
{
	char *hosten[] =
		{ "test", "ing", "this", -1};
}

Code:

$ gcc -o oddprog tomfoolery.c
tomfoolery.c: In function `main':
tomfoolery.c:6: warning: initialization makes pointer from integer without a cast

Lets say that we forget -1 for a moment, what I would like to understand is why would char** h_aliases accept an integer as the last argument and not a string?

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