Accept function

Synopsis

#include <winsock2.h>
int accept(
    SOCKET s,
    struct sockaddr *addr,
    int *addrlen
);

Description

The accept function extracts the first pending connection request on the listening socket s, creates a new socket for the connection, and returns the descriptor of that new socket. The original socket s remains open and can be used to accept further connections.

Parameters

Parameter	Description
`s`	Descriptor of a socket that is bound to a local address and is listening for connections.
`addr`	Pointer to a `sockaddr` structure that receives the address of the connecting entity. Can be `NULL` if not needed.
`addrlen`	Pointer to an integer that specifies the size of the `addr` buffer. On return, it contains the actual size of the address.

Return Value

On success, returns a new socket descriptor for the accepted connection. On error, returns INVALID_SOCKET and WSAGetLastError provides the error code.

Remarks

The returned socket inherits the properties of the listening socket.
Use closesocket to close the returned socket when finished.
After calling accept, the listening socket can continue to accept more connections.
For non‑blocking sockets, accept returns INVALID_SOCKET with WSAEWOULDBLOCK if no connections are pending.

Example

#include <winsock2.h>
#pragma comment(lib, "Ws2_32.lib")

int main() {
    WSADATA wsa;
    SOCKET listenSock, clientSock;
    struct sockaddr_in server, client;
    int clientLen = sizeof(client);

    WSAStartup(MAKEWORD(2,2), &wsa);
    listenSock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons(8080);
    bind(listenSock, (struct sockaddr*)&server, sizeof(server));
    listen(listenSock, SOMAXCONN);

    clientSock = accept(listenSock, (struct sockaddr*)&client, &clientLen);
    if (clientSock != INVALID_SOCKET) {
        const char *msg = "Hello from server!\n";
        send(clientSock, msg, (int)strlen(msg), 0);
        closesocket(clientSock);
    }
    closesocket(listenSock);
    WSACleanup();
    return 0;
}

Windows API Reference