通过网络编程实现客户端与服务器端程序设计，客户端发出一个数值，服务器端计算圆的面积并返回给客户端，请讲程序代码和运行结果截图上交。

在网络编程中，通常使用TCP/IP协议栈来实现实时通信。这里是一个简单的Python示例，展示了客户端如何发送一个数值到服务器，服务器计算圆的面积并返回结果。请注意，由于这是一个文本环境，我无法提供实际的运行结果截图。

**服务器端代码 (server.py)**:

import socket

def calculate_circle_area(radius):
    area = 3.14 * radius ** 2
    return f"Circle area for {radius} is {area}"

def main():
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.bind(('localhost', 12345))
    server_socket.listen(1)

    while True:
        client_connection, addr = server_socket.accept()
        request_data = client_connection.recv(1024).decode('utf-8')
        radius = float(request_data)
        response = calculate_circle_area(radius)
        client_connection.sendall(response.encode('utf-8'))
        client_connection.close()

if __name__ == "__main__":
    main()

**客户端代码 (client.py)**:

import socket

def send_request(radius):
    try:
        client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        client_socket.connect(('localhost', 12345))
        client_socket.sendall(str(radius).encode('utf-8'))
        received_data = client_socket.recv(1024).decode('utf-8')
        print(f"Received: {received_data}")
        client_socket.close()
    except Exception as e:
        print(f"Error: {e}")

if __name__ == "__main__":
    radius = input("Enter the radius of the circle: ")
    send_request(radius)

运行客户端，输入圆的半径，然后服务器会计算并返回圆的面积。例如，如果输入半径为`5`，预期结果可能是`Received: Circle area for 5.0 is 78.5`。