How to use gethostbyname in c

Question

I'm trying to use the function gethostbyname, but my code:

int handleTCP(char *hostname, char* portNo){

    struct hostent *hp = gethostbyname(hostname);

    ...

}

Keeps returning:

21: warning: initialization makes pointer from integer without a cast

Does anyone know what is wrong with my syntax?

thanks

if Evan's answer was not what was the problem: show us more code, especially whether line-number 21 is one of the ones you show us. — Bernd Elkemann, Nov 29 '11 at 22:33
Have you definitely got `#include ` at the top of your code? — Oliver Charlesworth, Nov 29 '11 at 22:33

score 3 · Accepted Answer · answered Nov 29 '11 at 22:32

3

You forgot to #include <netdb.h>. Because you didn't include this file, you are running into the "default int" rule. Basically, in C, if a function has no prototype, it is assumed to be:

int function_name(); in other words "returns an int, takes unknown number of parameters".

Properly declaring the function prototype (in this case by including the header) will avoid this.

answered Nov 29 '11 at 22:32

Evan Teran

87,561
32
179
238

Thanks. This fixed it. Silly mistake by me. – KWJ2104 Nov 29 '11 at 22:33

score 0 · Answer 2 · answered Nov 29 '11 at 22:33

I think you forgot to include netdb.h header file, so that compiler knows nothing about gethostbyname function and assumes that it returns integer. Then it complaints because in that case you would have converted integer to a pointer. You need to include a header to provide compiler with correct type information.

How to use gethostbyname in c

2 Answers2