Dart Basics
Variables, const/final, data types, null safety, collections, control flow, functions, closures
1What is the difference between var and dynamic in Dart?
What is the difference between var and dynamic in Dart?
답변
var determines the type at compile time based on the assigned value and remains fixed afterwards, while dynamic allows changing the type at any moment during runtime. Using var when the type is known provides better type safety and optimal performance as the compiler can perform static checks.
2What is the difference between const and final in Dart?
What is the difference between const and final in Dart?
답변
final allows assigning a value only once, but this value can be determined at runtime. const creates a compile-time constant whose value must be known before execution. const is more restrictive and enables additional optimizations as const objects are canonicalized and shared in memory.
3What does the ? suffix mean in a Dart type like String?
What does the ? suffix mean in a Dart type like String?
답변
The ? suffix indicates that a variable can contain null in addition to its normal value. This is the foundation of null safety introduced in Dart 2.12. Without this suffix, the variable can never be null, eliminating NullPointerExceptions at compile time. This approach ensures null errors are detected before execution.
Which operator should be used to safely access a property of a potentially null object?
What does the ?? operator do in Dart?
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