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Creating an Operation

Part of the Fundamentals section of Coddy's Dart journey. Lesson 89 of 94.

Challenge

Easy

Our calculator needs to know which operation to perform. To represent this, we'll use a string variable that can hold one of the four basic arithmetic operators: +, -, *, or /.

Update your calculator program to:

Declare a string variable named operation
Initialize it with the multiplication operator: "*"
Add a conditional statement that checks if the operation is valid (equal to '+', '-', '*', or '/')
If the operation is not valid, set it to '+' and print exactly: "Invalid operation. Using addition (+) as default."
Print "Operation: " followed by the operation value

Try it yourself

void main() {
  print("Welcome to the Simple Calculator!");
  
  // Declare and initialize number variables
  double firstNumber = 10.5;
  double secondNumber = 5.5;
  
  // Print the numbers
  print("First number: $firstNumber");
  print("Second number: $secondNumber");
  
  // Declare and validate the operation variable
}

All lessons in Fundamentals

1Introduction to Dart

What is Dart?The main Function Printing Output Code Comments

4Operators Part 2

Comparison Operators Logical AND Logical OR Logical NOT Type Test Operators Recap - Making Comparisons

7Working with Strings

String Concatenation String Interpolation Multi-line Strings String Properties Basic String Methods

10Collections - Maps Basics

What are Maps?Creating a Map Accessing Values by Key Key-Value Pairs Getting Map Size Getting Keys Getting Values Checking if a Key Exists

13Null Safety In Depth

Understanding Null Nullable Types Non-Nullable Types Null Assertion Operator Late Initialization Recap - Handling Null Safely

16Fundamentals Challenges

Challenge: List of calculation Challenge: Sum of numbers Challenge: Find product

3Operators Part 1

Arithmetic Operators Integer Division Modulo Operator Increment and Decrement Assignment Shortcuts Recap - Simple Calculations

6Control Flow - Decision Making

The 'if' Statement The 'else' Statement The 'else if' Statement Recap - Simple Decisions Nested 'if' Statements The 'switch' Statement

9Collections - Lists Basics

What are Lists?Creating a List Accessing by Index Getting List Length Adding Elements Removing Elements Checking if a List is Empty Iterating Over a List

12Functions Advanced

Optional Positional Parameters Named Parameters Required Named Parameters Default Parameter Values Recap - Function Parameters

15Project: Simple Calculator

Setting Up Declaring Number

Project lesson

Creating an Operation Project lesson

Project lesson

Performing Calculation

Project lesson

Displaying Result

Project lesson

Practice on your own: Online Dart compiler