Q1. What is a dictionary in Python?
A dictionary is an unordered, mutable collection of key-value pairs.
Keys must be unique and hashable (immutable), values can be any type.
Created with curly braces or dict().
Example:
Keys must be unique and hashable (immutable), values can be any type.
Created with curly braces or dict().
Example:
d = {"name": "Alice", "age": 30}Q2. How do you add and remove items from a dictionary?
Add by assignment: d["key"] = value.
Remove using del d["key"] or pop(key) which returns the value.
Clear all with clear().
Example:
Remove using del d["key"] or pop(key) which returns the value.
Clear all with clear().
Example:
d["city"] = "NYC"
value = d.pop("age")
del d["name"]Q3. What are the methods to iterate over a dictionary?
You can iterate over keys, values, or items (key-value pairs).
Example:
Example:
for key in d:
print(key, d[key])
for value in d.values():
print(value)
for key, value in d.items():
print(key, value)Q4. What is the difference between dict.get() and direct access?
Direct access (d[key]) raises KeyError if the key does not exist.
get(key, default) returns default (or None) if key missing, avoiding exceptions.
Example:
get(key, default) returns default (or None) if key missing, avoiding exceptions.
Example:
value = d.get("missing", "default")Q5. What are dictionary comprehensions?
Similar to list comprehensions, they create dictionaries.
Example:
Example:
squares = {x: x**2 for x in range(5)}