Lesson 3.6 – Dictionaries: Iteration & Methods

What we’ll learn today

• Looping through dictionaries
• Dictionary methods (get, update, del)
• Practical dictionary exercises

Quick Review

• How do you add a new key to a dictionary?
• How do you remove a key?

Looping Through Keys

student = {"name": "Alice", "age": 16, "grade": "10th"}
for key in student:
    print(key)

Looping Through Values

for value in student.values():
    print(value)

Looping Through Both

for key, value in student.items():
    print(key, ":", value)

Using get()

• Safer than square brackets

print(student.get("name"))     # Alice
print(student.get("gpa", "N/A"))

Updating Dictionaries

student.update({"age": 17, "gpa": 3.9})
print(student)

Deleting Keys

del student["grade"]
print(student)

Class Question

• Why might get() be safer than student["key"]?

Mini Practice

1. Create a dictionary with 3 countries and their capitals.
2. Loop through and print Country: Capital.

Mini Challenge

• Write a program that:
  1. Creates a dictionary of 3 friends and their favorite foods
  2. Loops through to print each name and food
  3. Uses update() to change one food
  4. Prints the dictionary after the update