Summary - Operators
- Dart course
- Beginner
- Lesson 29/116
- 5 min
Combine arithmetic, null-aware and logical operators to build a grade calculator.
Summary - Operators
In this group you learned Dart's operators: arithmetic (+ - * / % ~/), assignment (= += ++ --), comparison (== != < > <= >=), logical (&& || !) and null-aware (?? ?. ??=).
Combining them you can write a real grade calculator. We will practice with two small tasks.
In later lessons we will use these operators in collections, conditional expressions and more complex operations. The foundation is laid here.
Practice Calculate grade
Declare var score = 75;. Print the result with print('Passed: ${score >= 50}'). ${score >= 50} gives a bool result (true).
Starter code
// Calculate the gradeSample solution
void main() {
var score = 75;
print('Passed: ${score >= 50}');
}Expected output
Passed: true
Practice Final grade calculator
Declare var score = 85;. Get a bool result with var passed = score >= 50;. Print with print(passed). Expected output: true.
Starter code
// Final grade calculatorSample solution
void main() {
var score = 85;
var passed = score >= 50;
print(passed);
}Expected output
true
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Passing grade is 50 and above. Which condition is correct?
- score <= 50
- score > 50
- score = 50
- score >= 50 Correct answer
Explanation: >= is used for 50 and above.
2 Default value
int? x; print(x ?? ____);int? x; print(x ?? 0);Explanation: If x is null, 0 is printed.
3 Match all operators
| Term | Meaning |
|---|---|
+ |
Addition |
&& |
And |
?? |
Default |
== |
Equal |