Check whether a key exists in dictionary Dry Run in PYTHON

Check whether a key exists in dictionary is an interactive PYTHON dry run visualizer from the Dict programs section. Study the source code, then use the execution controls to follow each step, variable update, highlighted line, and console output.

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Check whether a key exists in dictionary Program Code

# Check key existence in dictionary
user = {
    "course": "Python Basics",
    "duration": "4 weeks",
    "enrolled": 150,
    "rating": 4.8
}
print("Dictionary:", user)

# Method 1: 'in' operator (most common)
keys_to_check = ["course", "instructor", "enrolled", "price"]
print("\nUsing 'in' operator:")
for key in keys_to_check:
    if key in user:
        print(f"  '{key}' exists with value: {user[key]}")
    else:
        print(f"  '{key}' does NOT exist")

# Method 2: get() method
print("\nUsing get() method:")
value = user.get("email", "Not found")
print(f"  email: {value}")
value = user.get("phone", "Not found")
print(f"  phone: {value}")

# Method 3: try-except
print("\nUsing try-except:")
try:
    print(f"  age: {user['age']}")
    print(f"  salary: {user['salary']}")
except KeyError as e:
    print(f"  KeyError: {e} not found")

# Method 4: Using setdefault (gets value or sets default)
phone = user.setdefault("phone", "N/A")
print(f"\nUsing setdefault(): phone = {phone}")
print(f"Dictionary after setdefault: {user}")

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