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Update Stock

Part of the Logic & Flow section of Coddy's Python journey — lesson 69 of 78.

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Challenge

Easy

Create a function named update_stock that takes two arguments: item (string) and quantity (int). The function should:

  1. Check if the item exists in the inventory dictionary.
    • If it does not exist, print "Error: Item '<item>' not found.".
  2. If the item exists, calculate the new stock by adding the quantity to the current stock.
    • If the new stock is negative, print "Error: Insufficient stock for '<item>'." and do not update.
    • Otherwise, update the stock in the inventory.
  3. Print "Stock for '<item>' updated successfully.".

Add (replace) the following block of code at the bottom of your code:

add_item("Apple", 0.5, 100)
add_item("Banana", 0.2, 50)
add_item("Apple", 0.6, 30)  # Should print an error
update_stock("Apple", -20)
update_stock("Banana", 30)
update_stock("Orange", 10)  # Should print an error
update_stock("Apple", -90)
print(inventory)

Try it yourself

inventory = {}

def add_item(item, price, stock):
    if item in inventory:
        print(f"Error: Item '{item}' already exists.")
        return
    try:
        inventory[item] = {"price": float(price), "stock": int(stock)}
        print(f"Item '{item}' added successfully.")
    except ValueError:
        print("Error: Price and stock must be numeric.")


add_item("Apple", 0.5, 100)
add_item("Banana", 0.2, 50)
add_item("Apple", 0.6, 30)  # Should print an error
print(inventory)

All lessons in Logic & Flow

1Variables Exploration

ConstantsMultiple Variable AssignmentsSwapping VariablesPlaceholder VariablesRound NumbersList Casting

4Contact Book Application

Display MenuAdd ContactProject lessonView ContactProject lessonEdit ContactProject lessonDelete ContactProject lessonList AllProject lessonEverything TogetherProject lesson

7Sets Part 2

Mathematical Operations Part 1Mathematical Operations Part 2Recap - Treasure HuntSubsets and SupersetsIterating Over SetsRecap - Tournament Tracker

10Basic List Comprehensions

The SyntaxCreating Simple ListsAdding ConditionsUsing Data AggregationRecap - House Of ListsRecap - Elements Of Freedom

13Inventory Management System

Project OverviewAdd ItemProject lessonUpdate StockProject lessonCheck AvailabilityProject lessonGenerate ReportProject lesson

2Dictionaries Part 1

What is a Dictionary?Creating a DictionaryAccessing ValuesModifying DictionariesRecap - Recipe Manager

5Advanced Decision Making

Ternary OperatorMembership ChecksIdentity ChecksIndentation ErrorsRecap - Vacation Filter

8Student Records Manager

Project OverviewAdd StudentProject lessonAdd GradeProject lessonIs EnrolledProject lessonAverage GradeProject lessonList by CourseProject lessonTop StudentsProject lesson

11Advanced Functions

Returning Multiple ValuesLambda Functions Part 1Lambda Functions Part 2Recap Challenge - Lambda SortRecursive Functions Part 1Recursive Functions Part 2Recap - Sum Nested List

14Higher-Order Functions

The Map FunctionThe Filter FunctionRecap - Email ValidatorRecap - Number Processor

3Dictionaries Part 2

Dictionary MethodsNested DictionariesChecking for KeysLooping Through DictionariesRecap - Frequency Counter

6Sets Part 1

What is a Set?Basic OperationsSet MethodsRecap - Remove Duplicates

9Advanced Data Aggregation

Using SumFinding Minimum and MaximumSorting Data EfficientlyRecap - Dictionary Sorter

12Basic Error Handling

What is Error Handling?The Try and Except BlockHandling Multiple ExceptionsRecap - Shopping Cart Errors

15Final Challenges

Smart Contact ManagerWord AnalyticsData Transformer