initial

SimpleClient.cpp

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+#include "SimpleClient.h"
+#include <iostream>
+#include <stdexcept>
+
+// 1. THE CONSTRUCTOR (Birth)
+// We initialize the socket to INVALID. We haven't bought a telephone yet.
+SimpleClient::SimpleClient() : clientSocket(INVALID_SOCKET) {}
+
+// 2. THE DESTRUCTOR (Cleanup)
+// When the Client object is destroyed, we must hang up the phone.
+SimpleClient::~SimpleClient() {
+    if (clientSocket != INVALID_SOCKET) {
+        CLOSE_SOCKET(clientSocket);
+    }
+}
+
+// 3. THE CONNECT METHOD (The Dialing Algorithm)
+bool SimpleClient::connectTo(const std::string& ip, int port) {
+    
+    // =========================================================================
+    // STEP 1: CREATE THE SOCKET (Buying the physical telephone)
+    // =========================================================================
+    // Just like the server, we need a physical socket to communicate.
+    // AF_INET = IPv4, SOCK_STREAM = Reliable TCP connection.
+    clientSocket = socket(AF_INET, SOCK_STREAM, 0);
+    if (clientSocket == INVALID_SOCKET) {
+        std::cerr << "❌ Failed to create client socket!\n";
+        return false;
+    }
+
+    // =========================================================================
+    // STEP 2: SETUP THE ADDRESS (Looking up the phone number)
+    // =========================================================================
+    // We need to tell the OS *who* we want to call.
+    sockaddr_in serverAddr{};
+    serverAddr.sin_family = AF_INET;       // IPv4
+    serverAddr.sin_port = htons(port);     // The port number (e.g., 8080)
+
+    // inet_pton = "Internet Presentation to Network"
+    // It converts the human-readable text "127.0.0.1" into the 32-bit binary 
+    // number that the computer's network card actually understands.
+    if (inet_pton(AF_INET, ip.c_str(), &serverAddr.sin_addr) <= 0) {
+        std::cerr << "❌ Invalid IP address format!\n";
+        return false;
+    }
+
+    // =========================================================================
+    // STEP 3: CONNECT (Dialing the number and waiting for an answer)
+    // =========================================================================
+    // This function BLOCKS (pauses) the program here until the server picks up.
+    // If the server isn't running, or the port is wrong, this will fail.
+    if (connect(clientSocket, reinterpret_cast<sockaddr*>(&serverAddr), sizeof(serverAddr)) == SOCKET_ERROR) {
+        std::cerr << "❌ Failed to connect to server at " << ip << ":" << port << "\n";
+        return false; // We couldn't get through, so we return false.
+    }
+
+    // If we reach here, the connection is successful! The line is open.
+    return true;
+}
+
+// 4. THE TALK METHOD (The Conversation Algorithm)
+void SimpleClient::talk(const std::string& message) const {
+    // Safety check: Don't try to talk if we aren't connected!
+    if (clientSocket == INVALID_SOCKET) {
+        std::cerr << "⚠️ Cannot talk: Not connected to a server.\n";
+        return;
+    }
+    
+    std::cout << "📤 Sending: " << message;
+
+    // =========================================================================
+    // STEP 4: SEND (Speaking into the microphone)
+    // =========================================================================
+    // We push our text message out through the open connection.
+    // We cast the length to 'int' to satisfy Windows, and it's perfectly safe 
+    // because our messages are small.
+    send(clientSocket, message.c_str(), static_cast<int>(message.length()), 0);
+
+    // =========================================================================
+    // STEP 5: RECV (Listening for the echo)
+    // =========================================================================
+    char buffer[1025]; // Our listening box (1024 data + 1 for '\0')
+    
+    // We BLOCK (wait) here until the server sends data back to us.
+    // We read up to 1024 bytes, leaving 1 byte for the stop-sign.
+    auto bytesReceived = recv(clientSocket, buffer, sizeof(buffer) - 1, 0);
+
+    if (bytesReceived > 0) {
+        // Convert to safe size_t for array indexing
+        const auto len = static_cast<size_t>(bytesReceived);
+        
+        // Add the invisible C-string stop-sign
+        buffer[len] = '\0';
+        
+        std::cout << "📥 Server echoed back: " << buffer << "\n";
+    } else {
+        // If bytesReceived is 0, the server hung up on us politely.
+        // If < 0, the connection broke.
+        std::cerr << "⚠️ Server disconnected or error occurred while waiting for echo.\n";
+    }
+}
+// Note: We do NOT call CLOSE_SOCKET() here. 
+// We want to keep the line open so the user can call talk() multiple times!
+// The destructor (~EchoClient) will handle the final hang-up.