问题：编译Socket时候出现socket bind error:Socket operation on non-socket
时间：2014-7-14
解决：注意“==”和“=”的优先级，前者是大于后者的，故而在处理一些表达式的时候，注意加括号
注意：注意下面标注闪光字体的地方


#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define portnumber 3332

int main(int argc,char *argv[])
{
        int sockfd,new_fd;
        struct sockaddr_in server_addr;
        struct sockaddr_in client_addr;
        int sin_size;
        int nbytes;
        char buffer[1024];
        if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
        {
                fprintf(stderr,"socket error:%s\n\a",strerror(errno));
                exit(1);
        }
        bzero(&server_addr,sizeof(struct sockaddr_in));
        server_addr.sin_family=AF_INET;
        server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
        server_addr.sin_port=htons(portnumber);
        if(bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))!= 0 )
        {

                fprintf(stderr,"socket bind error:%s\n\a",strerror(errno));
                exit(1);
        }
        if((listen(sockfd,5))!= 0 )
        {

                fprintf(stderr,"socket lisen error:%s\n\a",strerror(errno));
                exit(1);
        }

        while(1)
        {
                sin_size=sizeof(struct sockaddr_in);
                if((new_fd= accept(sockfd,(struct sockaddr *)(&client_addr),&sin_size))==-1)
                {

                fprintf(stderr,"socket accept error:%s\n\a",strerror(errno));
                exit(1);

                }

                buffer[nbytes]=‘\0‘;
                printf("Server recevied %s\n",buffer);
                close(new_fd);

        }
}
                                                                                             
        char buffer[1024];
       if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)// 极为容易出错，函数（）跟一个值比较，尤其是类似于 变量1=函数（），这样的形式，=号的优先级为14，要远远低于==，<,>,
        {
                fprintf(stderr,"socket error:%s\n\a",strerror(errno));
                exit(1);
        }
        bzero(&server_addr,sizeof(struct sockaddr_in));
        server_addr.sin_family=AF_INET;
        server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
        server_addr.sin_port=htons(portnumber);
        if(bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))!= 0 )
        {

                fprintf(stderr,"socket bind error:%s\n\a",strerror(errno));
                exit(1);
        }
        if((listen(sockfd,5))!= 0 )
        {

                fprintf(stderr,"socket lisen error:%s\n\a",strerror(errno));
                exit(1);
        }

        while(1)
        {
                sin_size=sizeof(struct sockaddr_in);
                if((new_fd= accept(sockfd,(struct sockaddr *)(&client_addr),&sin_size))==-1)
                {

                fprintf(stderr,"socket accept error:%s\n\a",strerror(errno));
                exit(1);

                }

                buffer[nbytes]=‘\0‘;
                printf("Server recevied %s\n",buffer);
                close(new_fd);

        }
}
      // 网上这种错误很多，大致分为三类，1，类似于我红色标注的那样，sockfd赋值错误，这种低级错误，2，端口号乱设，portnumber 一定要大于1024， 3.   初始化   server_addr 出错，