How to close sockets in C (GCC on Linux)

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I'm completely new to C. And am following this yt tutorial on sockets. However he's using the close(sock) function. There's 2 problems:

There's no variable called


    sock

. The socket is called something else.

I can't find the close function. The compiler is saying that the function doesn't exist

Can you please explain. This question might seem a little too dumb. Here's the Client code:

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main()
    // Create a socket
    int network_socket; 
    network_socket = socket(AF_INET, SOCK_STREAM, 0);
    // Address for the socket
    struct  sockaddr_in server_address;
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(9002);
    server_address.sin_addr.s_addr = INADDR_ANY;
    int connection = connect(network_socket, (struct sockaddr *) &server_address, sizeof(server_address));
    printf("%d\n", connection);
    char response[256];
    recv(network_socket, &response, sizeof(response), 0);
    printf("%s\n", response);
    return 0;
                Right before the cut screen, you can see Eduanix actually correcting the close line: youtu.be/LtXEMwSG5-8?t=1406.
– fde-capu
                Feb 22, 2022 at 14:14
There's no variable called sock. The socket is called something else.
Yes, it's network_socket in your code. So you want close(network_socket);.
I can't find the close function. The compiler is saying that the function doesn't exist
You need #include <unistd.h>, which is where close() is declared. (If you look at man close you'll see this at the top.)
                Thanks! This answered all my questions. Still curious about what went wrong since the guy in the vid didn't include unistd.h. But that doesn't really matter because its working
– RushiSrinivas.K
                Aug 13, 2020 at 7:46
                @RushiSrinivas.K Obviously, another header must have been implicitly including unistd.h, which is why the tutorial's code didn't need to.  Don't rely on that.  If you need to use something from a particular header, then just include that header yourself. If it has already been included, that is OK (provided the header is using proper include guards, which 99% of the time will be the case)
– Remy Lebeau
                Aug 13, 2020 at 16:17
You need to pass the socket file descriptor as the argument for close(). Which, for your code, is network_socket. So, close() need to be called as close(network_socket);
Also, you need to use the <unistd.h> header for the close() function.
                Yes. The whole problem was not inluding unistd.h. The guy in the video didn't so I was confused
– RushiSrinivas.K
                Aug 13, 2020 at 7:47
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