How to detect if a specific key pressed using Python? - GeeksforGeeks

02 Dec, 2020
In this article, we will learn how can we detect if a specific key is pressed by the user or not.  Detecting a key is very important for a coder, as the whole execution of the program is just dependent on a single/pattern key press. You may experience in your day-to-day life that the whole ATM transaction can be either accepted or denied when you press the enter key just after your PIN. In the same way, you will see many live examples in your day-to-day life. The whole Module is divided into 3 segments, The 1st segment deal with simple integers, 2nd Alphanumerical characters and In 3rd we will use a python module to detect a key.
Method 1: Using pynput.
In this method, we will use pynput python module to detecting any key press. “pynput.keyboard” contains classes for controlling and monitoring the keyboard. It Calls pynput.keyboard.Listener. stop from anywhere, or return False from a callback to stop the listener. This library allows you to control and monitor input devices.
Approach:
Import key, Listener from pynput.keyboard
Create a with Statement: The with statement is used to wrap the execution of a block with methods defined by a context manager.
Define functions
For installation run this code into your terminal.
pip install pynput
Example 1: Here you will see which key is being pressed.
Python3
from pynput.keyboard import Key, Listener  def show(key):      print('\nYou Entered {0}'.format( key))      if key == Key.delete:        # Stop listener        return False  # Collect all event until releasedwith Listener(on_press = show) as listener:       listener.join()
Output:
Example 2: Here you can detect a specific key is being been pressed or not.
Python3
from pynput.keyboard import Key, Listener  def show(key):        if key == Key.tab:        print("good")              if key != Key.tab:        print("try again")              # by pressing 'delete' button     # you can terminate the loop     if key == Key.delete:         return False  # Collect all event until releasedwith Listener(on_press = show) as listener:    listener.join()
Output:
Method 2: 
Here we are taking an input from a user and detecting that the user has entered the specified Alphanumerical(characters representing the numbers 0 – 9, the letters A – Z (both uppercase and lowercase), and some common symbols such as @ # * and &.) or not.
Approach:
Take user input
Create a loop
Use condition
Print output
Code:
Python3
for _ in range(3):      user_input = input(" Please enter your lucky word or type 'END' to terminate loop: ")          if user_input == "geek":        print("You are really a geek")        break      elif user_input == "END":        break      else:        print("Try Again")
Output:
python-utility
Python
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