Socket connect to server, enter number and get reply test.

server.py

import socket
import threading

# Define the host and port
HOST = '0.0.0.0'  # Localhost (change as needed)
PORT = 65432        # Port to listen on (non-privileged ports are > 1023)

# Function to handle each client connection
def handle_client(conn, addr):
    print(f"Connected by {addr}")
    
    # Send a thank you message to the client upon connection
    thank_you_message = "Thank you for connecting! Please enter a number:\n"
    conn.sendall(thank_you_message.encode('utf-8'))
    
    while True:
        try:
            data = conn.recv(1024)
            if not data:
                break
            
            # Decode the received data
            received_number = data.decode('utf-8').strip()
            print(f"Received from {addr}: {received_number}")
            
            # Try to convert the received data to an integer
            try:
                number = int(received_number)
                response = f"The double of {number} is {number * 2}\n"
            except ValueError:
                response = "Please enter a valid number.\n"
            
            # Send the response back to the client
            conn.sendall(response.encode('utf-8'))
        except ConnectionResetError:
            print(f"Connection with {addr} lost.")
            break

    conn.close()
    print(f"Connection with {addr} closed.")

# Function to start the server and listen for connections
def start_server():
    # Create a socket object
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    
    # Bind the socket to the host and port
    server.bind((HOST, PORT))
    
    # Start listening with a maximum backlog of 5 connections
    server.listen(5)
    print(f"Server listening on {HOST}:{PORT}")
    
    while True:
        # Accept a new connection
        conn, addr = server.accept()
        
        # Create a new thread to handle the client connection
        client_thread = threading.Thread(target=handle_client, args=(conn, addr))
        client_thread.start()

# Run the server
if __name__ == "__main__":
    start_server()

python-client.py

import socket

# Define the server host and port
HOST = 'IPNUMBERSERVER'  # The server's hostname or IP address
PORT = 65432        # The port used by the server

def start_client():
    # Create a socket object
    client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    
    # Connect to the server
    client.connect((HOST, PORT))
    
    # Receive and print the welcome message from the server
    welcome_message = client.recv(1024).decode('utf-8')
    print(welcome_message)
    
    while True:
        # Enter a number and send it to the server
        number = input("Enter a number (or type 'exit' to quit): ")
        
        if number.lower() == 'exit':
            print("Closing connection...")
            break
        
        client.sendall(number.encode('utf-8'))
        
        # Receive the response from the server and print it
        response = client.recv(1024).decode('utf-8')
        print(response)
    
    # Close the connection after the loop ends
    client.close()

# Run the client
if __name__ == "__main__":
    start_client()

arduino-client.ino

#include <ESP8266WiFi.h> // For ESP8266
//#include <WiFi.h>       // For ESP32

// Replace with your network credentials
const char* ssid     = "your_SSID";     // Replace with your network SSID (name)
const char* password = "your_PASSWORD"; // Replace with your network password

// Define the server's IP address and port
const char* host = "192.168.1.100"; // Replace with your server's IP address
const int port = 65432;             // Server port

WiFiClient client;

void setup() {
  Serial.begin(115200);
  delay(10);

  // Connect to WiFi
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }

  Serial.println();
  Serial.println("WiFi connected.");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

  // Connect to the server
  Serial.print("Connecting to server at ");
  Serial.print(host);
  Serial.print(":");
  Serial.println(port);

  if (client.connect(host, port)) {
    Serial.println("Connected to server!");
    
    // Wait for the welcome message from the server
    while (client.available() == 0);

    // Read and print the welcome message
    while (client.available()) {
      char c = client.read();
      Serial.print(c);
    }
  } else {
    Serial.println("Connection failed.");
  }
}
void loop() {
  // Check if connected to the server
  if (client.connected()) {
    // Check if there is any serial input from the user
    if (Serial.available() > 0) {
      String input = Serial.readStringUntil('\n');
      input.trim(); 

      if (input.equalsIgnoreCase("exit")) {
        Serial.println("Closing connection...");
        client.stop(); // Disconnect from the server
        while (true);  // Stop the loop
      }

      // Send the number to the server
      client.println(input);

      // Wait for the server's response
      while (client.available() == 0);

      // Read and print the server's response
      while (client.available()) {
        char c = client.read();
        Serial.print(c);
      }
    }
  } else {
    Serial.println("Disconnected from server.");
    while (true); // Stop the loop
  }
}