To make a socket listen for incoming connections, you need to perform a few steps:

1. Create a socket using the socket() function from the <sys/socket.h> header. You specify the address family as AF_INET, the socket type as SOCK_STREAM for TCP, and set the protocol as 0.

   TEXT/X-C++SRC

   1int sockfd;
   2sockfd = socket(AF_INET, SOCK_STREAM, 0);

2. Set up the server address using the sockaddr_in structure. This structure contains fields such as sin_family for the address family, sin_addr.s_addr for the IP address, and sin_port for the port number. In this example, we set the sin_addr.s_addr to htonl(INADDR_ANY) to bind the socket to any available network interface, and we set the sin_port to the desired port number.

   TEXT/X-C++SRC

   1struct sockaddr_in serverAddr;
   2serverAddr.sin_family = AF_INET;
   3serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
   4serverAddr.sin_port = htons(8080);

3. Bind the socket to the server address using the bind() function. This associates the socket with the specified address and port.

   TEXT/X-C++SRC

   1int bindResult = bind(sockfd, (struct sockaddr*)&serverAddr, sizeof(serverAddr));

4. Finally, you can make the socket listen for incoming connections using the listen() function. You pass the socket descriptor and specify the maximum number of connections that can be queued using the second parameter. In this example, we set the maximum queue size to 10.

   TEXT/X-C++SRC

   1int listenResult = listen(sockfd, 10);

If any errors occur during these steps, you can check the return values of the relevant functions to handle them accordingly.

Once the socket is listening for connections, you can then accept incoming connections using the accept() function. This allows you to establish a connection with a client and start sending and receiving data.

Remember to close the socket when you're done with it by calling the close() function!

Here's an example code that demonstrates how to make a socket listen for connections:

1#include <iostream>
2#include <sys/socket.h>
3#include <netinet/in.h>
4
5int main() {
6  int sockfd;
7  struct sockaddr_in serverAddr;
8
9  // Create a socket
10  sockfd = socket(AF_INET, SOCK_STREAM, 0);
11
12  if (sockfd == -1) {
13    std::cout << "Failed to create socket" << std::endl;
14    return 1;
15  }
16
17  // Set up the server address
18  serverAddr.sin_family = AF_INET;
19  serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
20  serverAddr.sin_port = htons(8080);
21
22  // Bind the socket
23  int bindResult = bind(sockfd, (struct sockaddr*)&serverAddr, sizeof(serverAddr));
24
25  if (bindResult == -1) {
26    std::cout << "Failed to bind socket" << std::endl;
27    return 1;
28  }
29
30  // Listen for connections
31  int listenResult = listen(sockfd, 10);
32
33  if (listenResult == -1) {
34    std::cout << "Failed to listen for connections" << std::endl;
35    return 1;
36  }
37
38  std::cout << "Socket is now listening for connections" << std::endl;
39
40  return 0;
41}

xxxxxxxxxx

}

#include <iostream>

#include <sys/socket.h>

#include <netinet/in.h>

​

int main() {

  int sockfd;

  struct sockaddr_in serverAddr;

​

  // Create a socket

  sockfd = socket(AF_INET, SOCK_STREAM, 0);

​

  if (sockfd == -1) {

    std::cout << "Failed to create socket" << std::endl;

    return 1;

  }

​

  // Set up the server address

  serverAddr.sin_family = AF_INET;

  serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);

  serverAddr.sin_port = htons(8080);

​

  // Bind the socket

  int bindResult = bind(sockfd, (struct sockaddr*)&serverAddr, sizeof(serverAddr));

​

  if (bindResult == -1) {

    std::cout << "Failed to bind socket" << std::endl;

    return 1;

  }

​