Thread: Getting *pointer problem/error

Hello

I having problem with fd_set pointer.....

1st attempt:

test.h :

Code:

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <sys/time.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <netdb.h>
#include <ctype.h>

void testfdset(fd_set *test)
{
	FD_ZERO((struct fdset) &test);
}

test.c :

Code:

#include "test.h"

int main()
{
	fd_set testing;
	
	testfdset(&testing);
	
	return 0;
}

Error shown:

Code:

$ gcc test.c
In file included from test.c:1:0:
test.h: In function ‘testfdset’:
test.h:18:2: error: conversion to non-scalar type requested

2nd attempt

test.h :

Code:

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <sys/time.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <netdb.h>
#include <ctype.h>

void testfdset(fd_set *test)
{
	FD_ZERO((struct fdset *) &test);
}

test.c :

Code:

#include "test.h"

int main()
{
	fd_set testing;
	
	testfdset(&testing);
	
	return 0;
}

Error shown:

Code:

$ gcc test.c
In file included from test.c:1:0:
test.h: In function ‘testfdset’:
test.h:18:2: error: dereferencing pointer to incomplete type

Any solution to the pointer or reference problem?

Thanks

Originally Posted by draggy

Code:

void testfdset(fd_set *test)
{
	FD_ZERO((struct fdset) &test);
}

The problem is that FD_ZERO takes a pointer to a fd_set and you are already providing a pointer to your testfdset function. Therefor when you add the ampersand you get the address of the pointer, not the address of test.

Code:

void testfdset(fd_set *test)
{
    FD_ZERO(test);
}