MCQs on Dart Basics | Dart
Mastering Dart basics is essential for building robust Flutter applications. This chapter delves into variables, data types, constants, type inference, comments, and code structure for clean, maintainable code.
Chapter: Dart Basics – MCQs
1. Variables and Data Types
- Which keyword is used to declare a variable in Dart?
- a)
var - b)
val - c)
let - d)
int
- a)
- What is the data type of
3.14in Dart?- a)
int - b)
double - c)
num - d)
float
- a)
- What is the default value of an uninitialized variable in Dart?
- a)
null - b)
0 - c)
undefined - d)
""
- a)
- Which of the following is a valid way to declare a list in Dart?
- a)
var list = [1, 2, 3]; - b)
let list = {1, 2, 3}; - c)
val list = [1, 2, 3]; - d)
array list = [1, 2, 3];
- a)
- What is the supertype of all numeric types in Dart?
- a)
int - b)
double - c)
num - d)
Object
- a)
- How do you declare a map in Dart?
- a)
var map = {'key': 'value'}; - b)
let map = {'key': 'value'}; - c)
map = ('key', 'value'); - d)
dict map = ['key': 'value'];
- a)
- What is the output of
var x; print(x);in Dart?- a)
null - b)
undefined - c)
0 - d) An error
- a)
- What is the data type of a variable declared with
dynamicin Dart?- a) It has no specific type
- b) It is always a string
- c) It is fixed at runtime
- d) It can change type during runtime
- Which function is used to parse a string into an integer in Dart?
- a)
int.parse() - b)
string.toInt() - c)
toInt() - d)
parseInt()
- a)
- What does
iskeyword check in Dart?- a) If two variables are equal
- b) If a variable is null
- c) If a variable matches a specific type
- d) If a variable is greater than zero
2. Constants and Final
- What is the difference between
constandfinalin Dart?- a)
constis evaluated at runtime,finalat compile-time - b)
constis evaluated at compile-time,finalat runtime - c) Both are the same
- d) Neither can be used in Dart
- a)
- How do you declare a constant in Dart?
- a)
const pi = 3.14; - b)
let pi = 3.14; - c)
val pi = 3.14; - d)
var pi = 3.14;
- a)
- Which of the following is true about
finalvariables in Dart?- a) They must be initialized at compile-time
- b) They can only be initialized once
- c) Their values can be changed later
- d) They cannot be used with classes
- Can a
constvariable in Dart reference an object?- a) Yes, but the object must be immutable
- b) No, objects cannot be
const - c) Yes, and the object can change
- d) Only primitive types can be
const
- What is the output of the following code?
const a = 10; final b = 20; a = 30; print(b);- a) 30
- b) An error
- c) 20
- d) 10
3. Type Inference
- What is type inference in Dart?
- a) Manually specifying the type of a variable
- b) Automatically determining the type of a variable
- c) Declaring variables without initialization
- d) Assigning the wrong type to a variable
- Which of the following demonstrates type inference in Dart?
- a)
var x = 5; - b)
int x = 5; - c)
dynamic x = 5; - d)
x = 5;
- a)
- Can type inference be used with
finalvariables in Dart?- a) Yes, always
- b) No, never
- c) Only if the variable is explicitly typed
- d) Only with
const
- What happens if you declare a variable with
varand assign it a value of typeString?- a) The type of the variable becomes
String - b) The type remains
dynamic - c) The type cannot be determined
- d) An error occurs
- a) The type of the variable becomes
- What is the inferred type of the following variable?dartCopy code
var score = 85;- a)
dynamic - b)
int - c)
double - d)
num
- a)
4. Comments and Code Structure
- What symbol is used for a single-line comment in Dart?
- a)
// - b)
# - c)
/* - d)
<!
- a)
- How do you write a multi-line comment in Dart?
- a)
/* */ - b)
<!-- --> - c)
# - d)
//
- a)
- What is the purpose of comments in Dart code?
- a) To execute special commands
- b) To make code more readable and maintainable
- c) To declare constants
- d) To optimize runtime performance
- Which of the following is NOT a valid comment style in Dart?
- a)
/// - b)
// - c)
<!-- --> - d)
/* */
- a)
- What is the purpose of
///in Dart?- a) To write inline comments
- b) To document code for tools like DartDoc
- c) To indicate deprecated code
- d) To mark constants
- How does Dart organize code into blocks?
- a) Using braces
{} - b) Using parentheses
() - c) Using brackets
[] - d) Using indentation
- a) Using braces
- What is the main file that Dart starts executing from in a project?
- a)
main.dart - b)
start.dart - c)
index.dart - d)
app.dart
- a)
- How do you structure a Dart function?
- a)
return_type function_name(parameters) { body } - b)
function_name(parameters) { body } - c)
def function_name { body } - d)
function function_name { body }
- a)
- How do you return a value from a Dart function?
- a)
return value; - b)
yield value; - c)
return(value); - d)
value return;
- a)
- What is the standard entry point of a Dart application?
- a)
void main() { } - b)
start() { } - c)
index() { } - d)
application() { }
- a)
Answers Table
| Qno | Answer |
|---|---|
| 1 | a) var |
| 2 | b) double |
| 3 | a) null |
| 4 | a) var list = [1, 2, 3]; |
| 5 | c) num |
| 6 | a) var map = {'key': 'value'}; |
| 7 | a) null |
| 8 | d) It can change type during runtime |
| 9 | a) int.parse() |
| 10 | c) If a variable matches a specific type |
| 11 | b) const is evaluated at compile-time, final at runtime |
| 12 | a) const pi = 3.14; |
| 13 | b) They can only be initialized once |
| 14 | a) Yes, but the object must be immutable |
| 15 | b) An error |
| 16 | b) Automatically determining the type of a variable |
| 17 | a) var x = 5; |
| 18 | a) Yes, always |
| 19 | a) The type of the variable becomes String |
| 20 | b) int |
| 21 | a) // |
| 22 | a) /* */ |
| 23 | b) To make code more readable and maintainable |
| 24 | c) <!-- --> |
| 25 | b) To document code for tools like DartDoc |
| 26 | a) Using braces {} |
| 27 | a) main.dart |
| 28 | a) return_type function_name(parameters) { body } |
| 29 | a) return value; |
| 30 | a) void main() { } |