我想在Python中从键盘读取数据。 我尝试了这段代码:
nb = input('Choose a number')
print('Number%s \n' % (nb))
但它无法运行,无论是在Eclipse还是终端中,总是在问题处停止。我可以输入一个数字,但之后什么都不会发生。
你知道为什么吗?
使用
input('Enter your input:')
如果您使用的是Python 3。
如果您想要一个数值,只需进行转换:
try:
mode = int(input('Input:'))
except ValueError:
print("Not a number")
如果您使用的是Python 2,则需要使用raw_input
而不是input
。看起来你在混合使用两种不同版本的Python(Python 2.x和Python 3.x)……基本上这是正确的:
nb = input('Choose a number: ')
问题在于它只支持Python 3。如@sharpner所回答的那样,对于旧版本的Python(2.x),您必须使用raw_input
函数:
nb = raw_input('Choose a number: ')
如果你想将其转换为数字,那么你应该尝试:
number = int(nb)
...但需要注意这可能会引发异常:
try:
number = int(nb)
except ValueError:
print("Invalid number")
如果你想使用格式化输出数字,在Python 3中建议使用str.format()
:
print("Number: {0}\n".format(number))
改为:
print('Number %s \n' % (nb))
但是在Python 2.7和Python 3中,str.format()
和%
两种选项都可以使用。
Enter Tel: 12340404
,而不是 Enter Tel12340404
。注意空格的重要性。 :P - Mehradimport 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()
"""
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://dev59.com/iXI-5IYBdhLWcg3w8NOB
- 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()
$ python3 read_keyboard_input.py
准备接收键盘输入:
嘿
输入字符串 = 嘿
你好
输入字符串 = 你好
7000
输入字符串 = 7000
退出
输入字符串 = 退出
退出串口终端。
结束。
请注意,Queue.put()
和Queue.get()
以及其他Queue类方法都是线程安全的!(这与C++标准模板库中的队列和其他容器不同!)由于Python的Queue类及其方法是线程安全的,这意味着它们实现了所有内部锁定语义,以便进行线程间操作,因此队列类中的每个函数调用都可以视为单个原子操作。请参阅文档顶部的注释:https://docs.python.org/3/library/queue.html(已加重):
你可以通过使用变量来简单地使用input()函数。快速示例!
user = input("Enter any text: ")
print(user)