keyboard.is_pressed() 无法正常工作

Question

I have some simple code to print "Hello" when I press my "ctrl" (control) key. Here is the code:

while(True):
    if keyboard.is_pressed('ctrl'):
        print("Hello")

This works but when I press my control key it prints 16 times instead of once. I tried using 'keyboard.read_key() == 'ctrl' but I got the same issue.

Answer 1

It is because the while is having no delay and the process keep entering in to the while loop. Although, the key press is just one from the user's perspective yet the computer is actually seeing multiple presses of those due to the while loop.

I am not sure how to effectively verify this but if we press the key just once and add a delay as below, we'll be able observe the difference:

import keyboard
import time
while(True):
    if keyboard.is_pressed('ctrl'):
        print("Hello")
        time.sleep(1)

Answer 2

I like to use the following logic:

if keyboard.is_pressed('ctrl'):
    keyboard.release('ctrl')
    time.sleep(0.1)
    """Do something"""

Depending on the application, you may need to make sure that the key is released before continuing, keyboard.release() comes in handy. I also agree with @KrishnaChaurasia that a delay must be added to make sure that the computer does not perform many cycles in what humans perceive as an instant.