Windows Platform Examples

Supported Systems

• Windows 10 or newer
• Other Windows systems with Winsock 2 or support like Windows 98 with ws2_32.dll

Why Windows is Different

Windows socket programming uses Winsock rather than the standard POSIX socket API.

Windows sockets require:

• Explicit initialization with WSAStartup()
• Explicit cleanup with WSACleanup()
• Windows-specific socket headers such as winsock2.h and ws2tcpip.h
• closesocket() instead of close()
• WSAGetLastError() instead of errno
• Linking against the Winsock library (Ws2_32)

Because of these differences, POSIX socket code cannot be reused directly on Windows without modification.

Supported Systems

• Windows
• Windows systems with MinGW/MSYS2 or another GCC-based toolchain
• Other Windows C development environments supporting Winsock

Windows TCP Client Example (client.c)

Purpose: Demonstrates how to:

• Initialize Winsock
• Create a TCP socket
• Connect to a remote server
• Send data over the connection
• Receive and print the response
• Close the socket and clean up Winsock

High-level Flow:

• Start Winsock with WSAStartup()
• Convert the IPv4 string into a network address with inet_addr()
• Create a TCP socket
• Connect to the remote server
• Send a request/message
• Receive the response
• Close the socket with closesocket()
• Clean up Winsock with WSACleanup()

Functions:

• WSAStartup()
• WSACleanup()
• socket()
• connect()
• send()
• recv()
• closesocket()
• inet_addr()
• WSAGetLastError()

Windows TCP Server Example (server.c)

Purpose: Demonstrates how to:

• Initialize Winsock
• Create a TCP listening socket
• Bind the socket to a local port
• Listen for incoming client connections
• Accept a client connection
• Send a simple response message
• Close sockets and clean up Winsock

High-level Flow:

• Start Winsock with WSAStartup()
• Create a TCP socket
• Bind the socket to a local port
• Place the socket into listening mode
• Accept one incoming client connection
• Send a simple message to the client
• Close the client socket
• Close the listening socket
• Clean up Winsock with WSACleanup()

Functions:

• WSAStartup()
• WSACleanup()
• socket()
• bind()
• listen()
• accept()
• send()
• closesocket()
• sockaddr_in
• htons()
• htonl()
• INADDR_ANY
• WSAGetLastError()

Notes

• The client and server must use the same port number in order to communicate.
• For local testing, the client can connect to 127.0.0.1.
• The example server is a simple TCP message server, not a full HTTP server.
• When building with GCC/MinGW, the program must be linked with -lws2_32.