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Python: Check whether a given key already exists in a dictionary

Python dictionary: Exercise-4 with Solution

Write a Python program to check whether a given key already exists in a dictionary.

Sample Solution-1:

Python Code:

d = {1: 10, 2: 20, 3: 30, 4: 40, 5: 50, 6: 60}
def is_key_present(x):
  if x in d:
      print('Key is present in the dictionary')
  else:
      print('Key is not present in the dictionary')
is_key_present(5)
is_key_present(9)

Sample Output:

Key is present in the dictionary                                                                              
Key is not present in the dictionary

Flowchart:

Flowchart: Check if a given key already exists in a dictionary

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Sample Solution-2:

Python Code:

def key_in_dict(d, key):
  return (key in d) 
students = {
  'Theodore': 19,
  'Roxanne': 22,
  'Mathew': 21,
  'Betty': 20
}
print("\nOriginal dictionary elements:")
print(students)
print(key_in_dict(students, 'Roxanne'))
print(key_in_dict(students, 'Gina'))

Sample Output:

Original dictionary elements:
{'Theodore': 19, 'Roxanne': 22, 'Mathew': 21, 'Betty': 20}
True
False

Flowchart:

Flowchart: Check if a given key already exists in a dictionary

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Python Code Editor:

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Next: Write a Python program to iterate over dictionaries using for loops.

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Python: Tips of the Day

Free up Memory:

  • Manual garbage collection can be performed on timely or event based mechanism.
import gc
collected_objects = gc.collect()