Question

I’m trying to set up a simple TCP socket in C++ without using any non-standard libraries.
I want to make a client socket and a server client and pass an integer to the server from the client. Can someone give me a simple example of a server and a client class?

Answer 1

C++ does not come with a “standard library” for sockets but can of course access the standard C library for sockets.

#include <sys/socket.h>

sockaddr_in addr;
bzero(&addr, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr(destination_address_as_32bit_number);
addr.sin_port = htons(destination_port_number_as_16bit_number);

int s = socket(AF_INET, SOCK_STREAM, 0);
connect(s, &addr, sizeof(addr));

There you go… Now you can read & write to “s” like any other file.
On the server you do it a bit different:

#include <sys/socket.h>

sockaddr_in addr;
bzero(&addr, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = 0; // bind to all interface addresses
addr.sin_port = htons(local_port_number_as_16bit_number);

int s = socket(AF_INET, SOCK_STREAM, 0);
bind(s, &addr, sizeof(addr));
listen(s, 50);  // 50 (the backlog) isn't really used on modern systems
int c = accept(s, &addr, sizeof(addr));  // addr gets info about client

An now you can read/write to “c” like any file. “s” is the listening socket on which you do nothing but accept().