c - Bind return error 88

Question

I'm trying to just bind a socket with this :

#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <errno.h>

int main()
{
    int fd,namelen,newfd;
    struct sockaddr_in sin = {AF_INET};

    if(fd=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)==-1)
      printf("socket : %d
",errno);

    if(bind(fd,(struct sockaddr *)&sin,sizeof(sin))==-1)
      printf("bind : %d
",errno);
}

And that return "bind : 88", I think this mean ENOTSOCK fd, isn't a socket really ? or 88 isn't ENOTSOCK ?

Answer 1

Take care about parenthesis, in fact fd = 0 in your case.
Because == is evaluated before = (see C Operator Precedence), your code is equivalent to fd = (socket(...) == -1).

You should replace

if(fd=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)==-1)

with

if((fd=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))==-1)