udp广播发送端为什么要绑定端口，感觉这个端口没有用上呀

Question

udp广播发送端为什么要绑定端口，感觉这个端口没有用上呀
int sfd = socket(AF_INET, SOCK_DGRAM, 0);
struct sockaddr_in addr;

memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(8788);
addr.sin_addr.s_addr=htonl(INADDR_ANY);

int ret = bind(sfd, (struct sockaddr *)&addr, sizeof(addr));

struct sockaddr_in cliaddr;
memset(&cliaddr,0,sizeof(cliaddr));
cliaddr.sin_family=AF_INET;
cliaddr.sin_port=htons(8787);
inet_pton(AF_INET, "192.168.50.255", &addr.sin_addr.s_addr);
int flag=1;
setsockopt(sfd,SOL_SOCKET,SO_BROADCAST,&flag,sizeof(flag));
socklen_t slen = sizeof(cliaddr);

Answer 1

bind里不就是关联起来了吗，分两处定义的，调用bind()后，就为socket套接字关联了一个相应的地址与端口号，即发送到地址值该端口的数据可通过socket读取和使用。