How to Check if a Key Exists in a Dictionary using Python

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In this tutorial, we’ll learn how to program "How to Check if a Key Exists in a Dictionary Using Python." The objective is to safely check if a key currently exists in a dictionary. This tutorial will demonstrate the process of verifying whether a specific key is present in a dictionary. A sample program will be provided to guide you through the implementation. So, let’s get started!

This topic is simple to understand. Just follow the instructions I provide, and you’ll be able to complete it with ease. The program I’ll demonstrate will show you the correct way to check if a key exists in a dictionary. So, let’s start coding!

Getting Started:

First you will have to download & install the Python IDLE's, here's the link for the Integrated Development And Learning Environment for Python https://www.python.org/downloads/.

Creating Main Function

This is the main function of the application. The following code will display a simple GUI in terminal console that will display program. To do this, simply copy and paste these blocks of code into the IDLE text editor.

1. d =
   
   {
   
   'a'
   
   : 1
   
   ,
   
   'b'
   
   : 2
   
   ,
   
   'c'
   
   : 3
   
   ,
   
   'd'
   
   : 4
   
   ,
   
   'e'
   
   : 5
   
   }
   
2. 
   
3. 
   
4. while
   
   True
   
   :
   
5. print
   
   (
   
   "\n
   
   ================= Check if a Key Exists in a Dictionary =================\n
   
   \n
   
   "
   
   )
   
6. print
   
   (
   
   d)
   
7. print
   
   (
   
   "\n
   
   "
   
   )
   
8. key =
   
   input
   
   (
   
   "Enter a key: "
   
   )
   
9. if
   
   key in
   
   d:
   
10. print
    
    (
    
    "Key already exist."
    
    )
    
11. else
    
    :
    
12. print
    
    (
    
    "Key does not exist."
    
    )
    
13. 
    
14. opt =
    
    input
    
    (
    
    "\n
    
    Do you want to try again?(yes/no): "
    
    )
    
15. 
    
16. if
    
    opt.lower
    
    (
    
    )
    
    ==
    
    'yes'
    
    :
    
17. ret=
    
    False
    
18. elif
    
    opt.lower
    
    (
    
    )
    
    ==
    
    'no'
    
    :
    
19. ret=
    
    True
    
20. print
    
    (
    
    "Exiting program...."
    
    )
    
21. else
    
    :
    
22. print
    
    (
    
    "Please enter yes/no:"
    
    )
    
23. break
    
24. 
    
25. if
    
    ret ==
    
    False
    
    :
    
26. continue
    

This program checks if a specified key exists in a dictionary. It starts with a predefined dictionary d = {'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}. The user is prompted to input a key. If the key exists in the dictionary, the program outputs "Key already exists." Otherwise, it outputs "Key does not exist." The process repeats in a loop until the user chooses to exit.

Output:

There you have it we successfully created How to Check if a Key Exists in a Dictionary using Python. I hope that this simple tutorial help you to what you are looking for. For more updates and tutorials just kindly visit this site. Enjoy Coding!

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