Dictionaries and key-value pairs in Intro to Computing - Flowchart & Logic Diagram

Process Overview

A dictionary is a way to store data using pairs of keys and values. Each key is unique and points to a value, like a label on a box telling you what is inside. This flowchart shows how to look up a value by its key in a dictionary.

Flowchart

Rectangle

Yes No↓

Rectangle

↓

Rectangle

This flowchart shows the steps to find a value in a dictionary by checking if the key exists and returning the value or a 'Key not found' message.

Step-by-Step Trace - 4 Steps

Step 1: Start and receive dictionary {'apple': 3, 'banana': 5} and key 'banana'

Step 2: Check if 'banana' is a key in the dictionary

Step 3: Return the value associated with 'banana'

Step 4: End the process

Diagram

Dictionary Memory Layout:
+-------------------+
| Key     | Value   |
+-------------------+
| 'apple' |   3     |
+-------------------+
| 'banana'|   5     |
+-------------------+

Lookup Process:
Key: 'banana' --> Find in keys --> Return 5

This diagram shows how the dictionary stores keys and values in pairs and how the lookup finds the value for a given key.

Flowchart Quiz - 3 Questions

What happens if the key is not found in the dictionary?

A Return the first value in the dictionary

B Return 'Key not found' message

C Add the key with a default value

D Stop without any message

Key Result

A dictionary stores data as unique keys paired with values, allowing quick lookup by checking if the key exists and returning its value.