Python 3.10 in macOS terminal
I kick off this simple script in macOS terminal, which runs infinitely (so please be warned when running it):
import itertools
for i in itertools.count(start=1):
try:
p = pow(2,i)
print(p)
except KeyboardInterrupt:
print("Loop terminated")
raise
Yet clicking on the keyboard does not terminate the loop.
What am I missing?
Thanks to everyone for the clarification. The problem is I was under the assumption that KeyboardInterrupt would respond to any key pressed. It actually only responds to Ctrl-C. Everything works as expected when using Ctrl-C.
I am very new to python. I have a little program and I want it run in the following order :
First I set a method time.sleep(10) within code to suspends execution for the 10 seconds in my test file.
I run my test file by command prompt.
While the program is performing a suspension of 10 seconds, suddenly I click the X close button in the top-right corner of the window, the program will not immediately shut down but it will run command print('Close terminal event detected.') and delay about 1 second by time.sleep(1) before it shuts off.
I wrote the code below but I'm still stuck. Would someone please tell me how to do it? Thank you.
import time
import os
time.sleep(10)
# If the terminal is closed while time.sleep(10) is running, the program will print the following line and run time.sleep(1) before exiting
print('Close terminal event detected.')
time.sleep(1)
You can define on_exit function and set it on win32api as True
import time
def on_exit(sig, func=None):
print('Close terminal event detected.')
time.sleep(1)
import win32api
win32api.SetConsoleCtrlHandler(on_exit, True)
print ("Executing")
time.sleep(10)
Executing will be printed and control goes to time.sleep(10)
As and when you hit exit, the event is detected and on_exit function is called.
Hence it will print Close terminal event detected. and then wait for a second and closes the window.
Hope that helps!
I run the following code in SublimeREPL:
while(True):
a = raw_input()
print a
How do I stop input when this is running? Ctrl+C, Ctlr+D, or Ctrl+Z don't seem to work like they do in a terminal.
You have to do ctrl+break or ctrl+space to break the infinite recursion and abort the program
I'm trying to write a very simple program that will wait for x seconds before checking to see it a key has been pressed then, depending on this outcome will go into a different loop further down the code. I have this code:
import msvcrt
import time
import sys
time.sleep(1)
if msvcrt.kbhit():
sys.stdout.write('y')
else:
sys.stdout.write('n')
So I press any key when it first starts (making kbhit ==true) but it always just falls to the second statement and prints 'n'.
Any suggestions what I'm doing wrong?
{Using Python 2.7 and IDLE}
Thanks
The msvcrt.kbhit() function will only work if the program it is in has been run from the windows command line (or if a console window is opened for its input and output when you double click on its .py file).
If you run from IDLE or using the pythonw.exe interpreter, the program won't be connected to a console window and the console-IO commands from msvcrt won't work.
I am running command-line Python scripts from the Windows taskbar by having a shortcut pointing to the Python interpreter with the actual script as a parameter.
After the script has been processed, the interpreter terminates and the output window is closed which makes it impossible to read script output.
What is the most straightforward way to keep the interpreter window open until any key is pressed?
In batch files, one can end the script with pause. The closest thing to this I found in python is raw_input() which is sub-optimal because it requires pressing the return key (instead of any key).
One way is to leave a raw_input() at the end so the script waits for you to press Enter before it terminates.
Try os.system("pause") — I used it and it worked for me.
Make sure to include import os at the top of your script.
There's no need to wait for input before closing, just change your command like so:
cmd /K python <script>
The /K switch will execute the command that follows, but leave the command interpreter window open, in contrast to /C, which executes and then closes.
The best option: os.system('pause') <-- this will actually display a message saying 'press any key to continue' whereas adding just raw_input('') will print no message, just the cursor will be available.
not related to answer:
os.system("some cmd command") is a really great command as the command can execute any batch file/cmd commands.
One way is to leave a raw_input() at the end so the script waits for you to press enter before it terminates.
The advantage of using raw_input() instead of msvcrt.* stuff is that the former is a part of standard Python (i.e. absolutely cross-platform). This also means that the script window will be alive after double-clicking on the script file icon, without the need to do
cmd /K python <script>
On Windows you can use the msvcrt module.
msvcrt.kbhit()
Return True if a keypress is waiting to be read.
msvcrt.getch()
Read a keypress and return the resulting character as a byte string. Nothing is echoed to the console. This call will block if a keypress is not already available, but will not wait for Enter to be pressed. If the pressed key was a special function key, this will return '\000' or '\xe0'; the next call will return the keycode. The Control-C keypress cannot be read with this function.
If you want it to also work on Unix-like systems you can try this solution using the termios and fcntl modules.
As to the "problem" of what key to press to close it, I (and thousands of others, I'm sure) simply use input("Press Enter to close").
There's a simple way to do this, you can use keyboard module's wait function. For example, you can do:
import keyboard
print("things before the pause")
keyboard.wait("esc") # esc is just an example, you can obviously put every key you want
print("things after the pause")
Getting python to read a single character from the terminal in an unbuffered manner is a little bit tricky, but here's a recipe that'll do it:
Recipe 134892: getch()-like unbuffered character reading from stdin on both Windows and Unix (Python)
On Windows 10 insert at beggining this:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
Strange, but it works for me! (Together with input() at the end, of course)
An external WConio module can help here: http://newcenturycomputers.net/projects/wconio.html
import WConio
WConio.getch()
import pdb
pdb.debug()
This is used to debug the script. Should be useful to break also.
If you type
input("")
It will wait for them to press any button then it will continue. Also you can put text between the quotes.