How to stop a function & exit program running in a while loop on key press?-CodePudding

I need to stop a program when a keyboard key q is pressed. How can I achieve that in the below code? How can I ignore time.sleep & detect a keypress & exit the program by printing something? Currently, the keypress gets detected only after 10 seconds. Suppose I am pressing q after 3 seconds the program doesn't exit.

import sys
import time

import keyboard

def hd():
    print("Hi")
    time.sleep(10)
    if keyboard.is_pressed("q"):
        print(keyboard.is_pressed("q"))
        sys.exit()


while True:
    hd()

CodePudding user response：

time.sleep() is a blocking call. Nothing happens in your program while it runs.

Shorten the intervals. For example, instead of sleeping 10 seconds, sleep 100 × 0.1 second.

import sys
import time

import keyboard

def hd():
    print("Hi")
    for _ in range(100):
        time.sleep(0.1)
        if keyboard.is_pressed("q"):
            print(keyboard.is_pressed("q"))
            sys.exit()

while True:
    hd()

For more complex behavior (doing actual work while also listening for a keyboard event) you will have to look into multithreading.

CodePudding user response：

Instead of polling the keyboard to check if a certain key is pressed, you can just add a hotkey. When the hotkey q (or whatever key you like) is pressed, a trigger function quit is called.

import keyboard
import time
import sys

exitProgram = False

# prepare to exit the program
def quit():
    global exitProgram
    exitProgram=True
    
# set hotkey    
keyboard.add_hotkey('q', lambda: quit())

# main loop to do things
while not exitProgram:
    print("Hello")
    time.sleep(1)
    
print("bye bye")
sys.exit()