新学C，有socket问题请教了。

[pwtitle]

#include <stdio.h>
#include <sys/types.h>
#include <string.h>
#include <sys/socket.h>

#define PORT 1234
#define SERVER_IP "127.0.0.1"

int main(int argc,char *argv[])
{

struct addr_in
{
unsigned char s_addr[16];
};
struct sockaddr_in{
unsigned short sin_family;
unsigned short int sin_port;
struct addr_in sin_addr;
unsigned char sin_zero[8];
};

int sockfd , errno;

struct sockaddr_in server_addr;

if(sockfd=socket(AF_INET,SOCK_STREAM,0)==-1){
fprintf(stderr,"Socket Error : %s \r\n",strerror(errno));
exit(1);
}


bzero(&server_addr,sizeof(struct sockaddr_in));
server_addr.sin_family=AF_INET;
server_addr.sin_addr.s_addr=htonl(SERVER_IP);
server_addr.sin_port=htons(PORT);


if(bind(sockfd,(struct sockaddr *)(& server_addr),sizeof(struct sockaddr_in))==-1)
{
fprintf(stderr,"Bind error : %s \r\n",strerror(errno));
exit(1);
}

if(listen(sockfd,5)==-1) {
fprintf(stderr,"Listen error : %s \r\n",strerror(errno));
exit(1);
}


return 1;
}



编译时候显示：
httpd.c: In function `main':
httpd.c:36: incompatible types in assignment

请教是哪里的问题？

[pwtitle]

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


#define PORT 1234
#define SERVER_IP "127.0.0.1"

int main(int argc,char *argv[])
{
int sockfd , errno;
struct sockaddr_in server_addr;

if( sockfd=socket(AF_INET,SOCK_STREAM,0) == -1 ){
fprintf(stderr,"Socket Error : %s \r\n",strerror(errno));
exit(1);
}

bzero( &server_addr , sizeof(struct sockaddr_in) );
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = inet_addr(SERVER_IP);
server_addr.sin_port = htons(PORT);


if( bind(sockfd,(struct sockaddr *)(& server_addr),sizeof(struct sockaddr_in)) == -1 )
{
fprintf(stderr,"Bind error : %s \r\n",strerror(errno));
exit(1);
}

if(listen(sockfd,5) == -1) {
fprintf(stderr,"Listen error : %s \r\n",strerror(errno));
exit(1);
}

return 1;
}


现在编译通过，但是在执行时候现实：
Bind error : Socket operation on non-socket

这是怎么搞的？

[sourceid]

把 if( sockfd=socket(AF_INET,SOCK_STREAM,0) == -1 ){
改为
if( (sockfd=socket(AF_INET,SOCK_STREAM,0)) == -1 ){