Day 13: Dictionaries — Find Any Data Instantly!

What's a Dictionary?

Open your phone contacts. You search "Priya" and instantly get her number. You didn't scroll through everyone — you searched by name and got the info. That's exactly how a Python dictionary works! Search by key, get the value instantly.

Creating a Dictionary

student = {
    "name": "Rohith",
    "age": 21
}

Curly brackets { } hold the dictionary. "name" is the key. "Rohith" is the value. Think of keys as labels and values as the information behind them!

Getting Values

print(student["name"])   # Rohith
print(student["age"])    # 21

Use the key in square brackets to get the value. Just like searching a name in your contacts to get their number!

Real World Connection

When you log into Instagram, your profile is stored as a dictionary — username, followers, bio, profile picture all linked to your account. When you order on Zomato, your order is a dictionary — items, price, address, status. Every user profile in every app is a dictionary!

Adding and Updating

student = {"name": "Rohith", "age": 21}

student["city"] = "Hyderabad"
student["age"] = 22

print(student)

Output: name Rohith, age 22, city Hyderabad. Adding a new key is like adding a new field to your profile. Updating is like changing your bio!

Common Mistakes

Mistake 1 — Missing quotes around the key.

print(student[name])     # WRONG
print(student["name"])   # CORRECT

Mistake 2 — Using square brackets instead of curly brackets.

student = ["name": "Rohith"]   # WRONG
student = {"name": "Rohith"}   # CORRECT

Mini Challenge

Quick Quiz

Q: What brackets do dictionaries use? A: Curly brackets { } — not square [ ] like lists!

Q: How do you get the "age" value from a dictionary called person? A: person["age"]

Q: What's the difference between a list and a dictionary? A: Lists use positions (0, 1, 2). Dictionaries use named keys ("name", "age")!

Key Takeaways