来自维基百科http://en.wikipedia.org/wiki/Berkeley_sockets#bind.28.29
connect()：
connect() 系统调用将由其文件描述符标识的套接字连接到由该主机在参数列表中的地址指定的远程主机。
某些类型的套接字是无连接的，最常见的是用户数据报协议套接字。对于这些套接字，connect 具有特殊含义：发送和接收数据的默认目标设置为给定地址，从而允许在无连接套接字上使用 send() 和 recv() 等函数。
connect() 返回一个表示错误代码的整数：0 表示成功，-1 表示错误。
绑定（）：
bind() 将一个套接字分配给一个地址。当使用 socket() 创建一个套接字时，它只被赋予了一个协议族，而没有分配一个地址。这种与地址的关联必须通过 bind() 系统调用执行，然后套接字才能接受到其他主机的连接。 bind() 接受三个参数：
sockfd，一个描述符，表示要在其上执行绑定的套接字。
my_addr，指向 sockaddr 结构的指针，表示要绑定到的地址。
addrlen，一个 socklen_t 字段，指定 sockaddr 结构的大小。
Bind() 成功时返回 0，发生错误时返回 -1。
示例：
1.)使用连接
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
int main(){
int clientSocket;
char buffer[1024];
struct sockaddr_in serverAddr;
socklen_t addr_size;
/*---- Create the socket. The three arguments are: ----*/
/* 1) Internet domain 2) Stream socket 3) Default protocol (TCP in this case) */
clientSocket = socket(PF_INET, SOCK_STREAM, 0);
/*---- Configure settings of the server address struct ----*/
/* Address family = Internet */
serverAddr.sin_family = AF_INET;
/* Set port number, using htons function to use proper byte order */
serverAddr.sin_port = htons(7891);
/* Set the IP address to desired host to connect to */
serverAddr.sin_addr.s_addr = inet_addr("192.168.1.17");
/* Set all bits of the padding field to 0 */
memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);
/*---- Connect the socket to the server using the address struct ----*/
addr_size = sizeof serverAddr;
connect(clientSocket, (struct sockaddr *) &serverAddr, addr_size);
/*---- Read the message from the server into the buffer ----*/
recv(clientSocket, buffer, 1024, 0);
/*---- Print the received message ----*/
printf("Data received: %s",buffer);
return 0;
}
2.)绑定示例：
int main()
{
struct sockaddr_in source, destination = {}; //two sockets declared as previously
int sock = 0;
int datalen = 0;
int pkt = 0;
uint8_t *send_buffer, *recv_buffer;
struct sockaddr_storage fromAddr; // same as the previous entity struct sockaddr_storage serverStorage;
unsigned int addrlen; //in the previous example socklen_t addr_size;
struct timeval tv;
tv.tv_sec = 3; /* 3 Seconds Time-out */
tv.tv_usec = 0;
/* creating the socket */
if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
printf("Failed to create socket\n");
/*set the socket options*/
setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv, sizeof(struct timeval));
/*Inititalize source to zero*/
memset(&source, 0, sizeof(source)); //source is an instance of sockaddr_in. Initialization to zero
/*Inititalize destinaton to zero*/
memset(&destination, 0, sizeof(destination));
/*---- Configure settings of the source address struct, WHERE THE PACKET IS COMING FROM ----*/
/* Address family = Internet */
source.sin_family = AF_INET;
/* Set IP address to localhost */
source.sin_addr.s_addr = INADDR_ANY; //INADDR_ANY = 0.0.0.0
/* Set port number, using htons function to use proper byte order */
source.sin_port = htons(7005);
/* Set all bits of the padding field to 0 */
memset(source.sin_zero, '\0', sizeof source.sin_zero); //optional
/*bind socket to the source WHERE THE PACKET IS COMING FROM*/
if (bind(sock, (struct sockaddr *) &source, sizeof(source)) < 0)
printf("Failed to bind socket");
/* setting the destination, i.e our OWN IP ADDRESS AND PORT */
destination.sin_family = AF_INET;
destination.sin_addr.s_addr = inet_addr("127.0.0.1");
destination.sin_port = htons(7005);
//Creating a Buffer;
send_buffer=(uint8_t *) malloc(350);
recv_buffer=(uint8_t *) malloc(250);
addrlen=sizeof(fromAddr);
memset((void *) recv_buffer, 0, 250);
memset((void *) send_buffer, 0, 350);
sendto(sock, send_buffer, 20, 0,(struct sockaddr *) &destination, sizeof(destination));
pkt=recvfrom(sock, recv_buffer, 98,0,(struct sockaddr *)&destination, &addrlen);
if(pkt > 0)
printf("%u bytes received\n", pkt);
}
我希望能澄清区别
请注意，您声明的套接字类型将取决于您的要求，这一点非常重要