sockaddr , in_addr区别

struct   sockaddr   {  
                unsigned   short   sa_family;     
                char   sa_data[14];     
        };  
  上面是通用的socket地址，具体到Internet   socket，用下面的结构，二者可以进行类型转换  
         
  struct   sockaddr_in   {  
                short   int   sin_family;     
                unsigned   short   int   sin_port;     
                struct   in_addr   sin_addr;     
                unsigned   char   sin_zero[8];     
        };  
        struct   in_addr就是32位IP地址。  
        struct   in_addr   {  
                union {
                        struct { u_char s_b1,s_b2,s_b3,s_b4; } S_un_b;
                        struct { u_short s_w1,s_w2; } S_un_w;
                        u_long S_addr; 
                } S_un;
                #define s_addr  S_un.S_addr
        };  
   inet_addr()是将一个点分制的IP地址(如192.168.0.1)转换为上述结构中需要的32位IP地址(0xC0A80001)。

//绑定socket
	struct sockaddr_in svraddr;
	svraddr.sin_family = AF_INET;
	svraddr.sin_port = htons(port);
	if(ip)
	{
		if (inet_addr(ip)!=INADDR_NONE)
			svraddr.sin_addr.s_addr = inet_addr(ip);
		else 
			return S_PARAMERR;
	}
	else
		svraddr.sin_addr.s_addr = INADDR_ANY;