非阻塞，多线程示例：

Question

我想在python

中读取键盘上的数据

我试试这个：

nb = input('Choose a number')
print ('Number%s \n' % (nb))

但它不起作用，既不是日食也不是终端，它总是停止问题。我可以输入一个数字，但什么也没发生。

你知道为什么吗？

Answer 1

尝试

raw_input('Enter your input:')  # If you use Python 2
input('Enter your input:')      # If you use Python 3

如果你想拥有一个数值只需转换它：

try:
    mode=int(raw_input('Input:'))
except ValueError:
    print "Not a number"

Answer 2

似乎你在这里混合不同的Pythons（Python 2.x与Python 3.x）...... 这基本上是正确的：

nb = input('Choose a number: ')

问题在于它仅在Python 3中受支持。正如@sharpner所回答的，对于旧版本的Python（2.x），您必须使用函数raw_input：

nb = raw_input('Choose a number: ')

如果您想将其转换为数字，那么您应该尝试：

number = int(nb)

...虽然您需要考虑到这会引发异常：

try:
    number = int(nb)
except ValueError:
    print("Invalid number")

如果您想使用格式打印数字，建议在Python 3中使用str.format()：

print("Number: {0}\n".format(number))

而不是：

print('Number %s \n' % (nb))

但是两个选项（str.format()和%）在Python 2.7和Python 3中都有效。

Answer 3

非阻塞，多线程示例：

由于键盘输入的阻塞（因为input()功能块）通常不是我们想要的（我们经常想继续做其他事情），所以这是< strong>非常精简的多线程示例，以演示如何在继续运行主应用程序的同时仍在每次输入键盘输入时读取它们。

这是通过创建一个在后台运行的线程，连续调用input()并将接收到的所有数据传递到队列来实现的。

这样，您的主线程就可以做任何想做的事情，只要队列中有内容，就从第一个线程接收键盘输入数据。

1。裸Python 3代码示例（无注释）：

import threading
import queue
import time

def read_kbd_input(inputQueue):
    print('Ready for keyboard input:')
    while (True):
        input_str = input()
        inputQueue.put(input_str)

def main():
    EXIT_COMMAND = "exit"
    inputQueue = queue.Queue()

    inputThread = threading.Thread(target=read_kbd_input, args=(inputQueue,), daemon=True)
    inputThread.start()

    while (True):
        if (inputQueue.qsize() > 0):
            input_str = inputQueue.get()
            print("input_str = {}".format(input_str))

            if (input_str == EXIT_COMMAND):
                print("Exiting serial terminal.")
                break

            # Insert your code here to do whatever you want with the input_str.

        # The rest of your program goes here.

        time.sleep(0.01) 
    print("End.")

if (__name__ == '__main__'): 
    main()

2。与上述相同的Python 3代码，但带有大量说明性注释：

"""
read_keyboard_input.py

Gabriel Staples
www.ElectricRCAircraftGuy.com
14 Nov. 2018

References:
- https://pyserial.readthedocs.io/en/latest/pyserial_api.html
- *****https://www.tutorialspoint.com/python/python_multithreading.htm
- *****https://en.wikibooks.org/wiki/Python_Programming/Threading
- https://stackoverflow.com/questions/1607612/python-how-do-i-make-a-subclass-from-a-superclass
- https://docs.python.org/3/library/queue.html
- https://docs.python.org/3.7/library/threading.html

To install PySerial: `sudo python3 -m pip install pyserial`

To run this program: `python3 this_filename.py`

"""

import threading
import queue
import time

def read_kbd_input(inputQueue):
    print('Ready for keyboard input:')
    while (True):
        # Receive keyboard input from user.
        input_str = input()

        # Enqueue this input string.
        # Note: Lock not required here since we are only calling a single Queue method, not a sequence of them 
        # which would otherwise need to be treated as one atomic operation.
        inputQueue.put(input_str)

def main():

    EXIT_COMMAND = "exit" # Command to exit this program

    # The following threading lock is required only if you need to enforce atomic access to a chunk of multiple queue
    # method calls in a row.  Use this if you have such a need, as follows:
    # 1. Pass queueLock as an input parameter to whichever function requires it.
    # 2. Call queueLock.acquire() to obtain the lock.
    # 3. Do your series of queue calls which need to be treated as one big atomic operation, such as calling
    # inputQueue.qsize(), followed by inputQueue.put(), for example.
    # 4. Call queueLock.release() to release the lock.
    # queueLock = threading.Lock() 

    #Keyboard input queue to pass data from the thread reading the keyboard inputs to the main thread.
    inputQueue = queue.Queue()

    # Create & start a thread to read keyboard inputs.
    # Set daemon to True to auto-kill this thread when all other non-daemonic threads are exited. This is desired since
    # this thread has no cleanup to do, which would otherwise require a more graceful approach to clean up then exit.
    inputThread = threading.Thread(target=read_kbd_input, args=(inputQueue,), daemon=True)
    inputThread.start()

    # Main loop
    while (True):

        # Read keyboard inputs
        # Note: if this queue were being read in multiple places we would need to use the queueLock above to ensure
        # multi-method-call atomic access. Since this is the only place we are removing from the queue, however, in this
        # example program, no locks are required.
        if (inputQueue.qsize() > 0):
            input_str = inputQueue.get()
            print("input_str = {}".format(input_str))

            if (input_str == EXIT_COMMAND):
                print("Exiting serial terminal.")
                break # exit the while loop

            # Insert your code here to do whatever you want with the input_str.

        # The rest of your program goes here.

        # Sleep for a short time to prevent this thread from sucking up all of your CPU resources on your PC.
        time.sleep(0.01) 

    print("End.")

# If you run this Python file directly (ex: via `python3 this_filename.py`), do the following:
if (__name__ == '__main__'): 
    main()

示例输出：

$ python3 read_keyboard_input.py
  准备进行键盘输入：
  嘿
  input_str =嘿
  你好
  input_str =你好
  7000
  input_str = 7000
  退出
  input_str =退出
  正在退出串行终端。
  结束。

参考：

Answer 4

input([prompt])相当于eval(raw_input(prompt))，自python 2.6

以来可用

由于它不安全（因为eval），raw_input应该是关键应用程序的首选。

Answer 5

这应该有效

yourvar = input('Choose a number: ')
print('you entered: ' + yourvar)

如何阅读键盘输入？

5 个答案:

非阻塞，多线程示例：

1。裸Python 3代码示例（无注释）：

2。与上述相同的Python 3代码，但带有大量说明性注释：

示例输出：

参考：