💪 Stay calm, read the subject twice, and commit often.
You must be comfortable with double pointers ( **ptr ) and understanding the difference between modifying a copy of a variable and modifying the variable itself.
When a client connects: Broadcast "server: client %d just arrived\n" .
Success depends on speed and accuracy. Use these "features" to structure your code: 1. The Essential Variable Set Maintain a global or struct-based state to keep your loop clean: int max_fd : The highest file descriptor currently open. fd_set master, read_fds : To track active sockets. int next_id : To assign incremental IDs to new clients. char *msgs[65536] : An array to buffer partial messages for each FD. 2. Socket Initialization Don't waste time—memorize the standard setup sequence: socket(AF_INET, SOCK_STREAM, 0) sockaddr_in sin_family sin_addr.s_addr with a high backlog (e.g., 128). 3. The Select Loop Logic Your main loop should follow this exact flow: select(max_fd + 1, &read_fds, NULL, NULL, NULL) on the Server Socket: the new client, them, update , and broadcast the "Server: client X joined" message. on a Client Socket: bytes <= 0 , and broadcast "Server: client X left". : Buffer the message and broadcast it to everyone else only when a is reached ⚠️ Common Pitfalls to Avoid Memory Leaks: your message buffers when a client disconnects. Zombie FDs: Ensure you update
Recursion is the bread and butter of the 42 early curriculum. By Exam 06, you are expected to move beyond simple recursive functions like ft_strlen or factorial . You will likely face problems where recursion is the only viable solution, or where iterative solutions are too complex to write within the time limit.
Exam 06 is notoriously known for testing your understanding of low-level networking and I/O multiplexing. Here is everything you need to know to conquer it. What is Exam 06?
system calls. This exam tests your ability to handle multiple client connections simultaneously without using threads, specifically focusing on the 🛠️ Core Technical Requirements The exam asks you to write a server that:
Sending messages one byte at a time is a recipe for a timeout. Use write() or send() effectively.
: The server must handle multiple clients simultaneously without blocking on a single connection .
: You don't need to write everything from scratch. Roughly 100 out of the ~150 lines required are often provided in the exam subject .