# Dart Basics (Flutter)

> Variables, const/final, data types, null safety, collections, control flow, functions, closures

- 25 interview questions
- Junior
- [Interview Questions: Flutter](https://sharpskill.dev/en/technologies/flutter/interview-questions.md)

## 1. What is the difference between var and dynamic in Dart?

**Answer**

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.

## 2. What is the difference between const and final in Dart?

**Answer**

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.

## 3. What does the ? suffix mean in a Dart type like String?

**Answer**

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.

## 22 more questions available

- 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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## Other Flutter interview topics

- [Dart Language Essentials](https://sharpskill.dev/en/technologies/flutter/interview-questions/dart-language-essentials.md): 15 questions, Junior
- [Flutter Fundamentals](https://sharpskill.dev/en/technologies/flutter/interview-questions/flutter-fundamentals.md): 18 questions, Junior
- [Widget Lifecycle](https://sharpskill.dev/en/technologies/flutter/interview-questions/widget-lifecycle.md): 20 questions, Junior
- [Local Storage](https://sharpskill.dev/en/technologies/flutter/interview-questions/local-storage.md): 20 questions, Junior
- [Application Lifecycle](https://sharpskill.dev/en/technologies/flutter/interview-questions/app-lifecycle.md): 20 questions, Junior
- [Layouts & Constraints](https://sharpskill.dev/en/technologies/flutter/interview-questions/layouts-constraints.md): 24 questions, Mid-Level
- [ListView & GridView](https://sharpskill.dev/en/technologies/flutter/interview-questions/listview-gridview.md): 25 questions, Mid-Level
- [Navigation & Routing](https://sharpskill.dev/en/technologies/flutter/interview-questions/navigation-routing.md): 22 questions, Mid-Level
- [Basic State Management](https://sharpskill.dev/en/technologies/flutter/interview-questions/state-management-basics.md): 22 questions, Mid-Level
- [Provider Pattern](https://sharpskill.dev/en/technologies/flutter/interview-questions/provider-pattern.md): 18 questions, Mid-Level
- [Networking & HTTP](https://sharpskill.dev/en/technologies/flutter/interview-questions/networking-http.md): 20 questions, Mid-Level
- [JSON Serialization](https://sharpskill.dev/en/technologies/flutter/interview-questions/json-serialization.md): 20 questions, Mid-Level
- [Local Database](https://sharpskill.dev/en/technologies/flutter/interview-questions/local-database.md): 22 questions, Mid-Level
- [Forms & Validation](https://sharpskill.dev/en/technologies/flutter/interview-questions/forms-validation.md): 20 questions, Mid-Level
- [Animations](https://sharpskill.dev/en/technologies/flutter/interview-questions/animations.md): 20 questions, Mid-Level
- [Firebase Integration](https://sharpskill.dev/en/technologies/flutter/interview-questions/firebase-integration.md): 18 questions, Mid-Level
- [Unit Testing](https://sharpskill.dev/en/technologies/flutter/interview-questions/unit-testing.md): 20 questions, Mid-Level
- [Widget Testing](https://sharpskill.dev/en/technologies/flutter/interview-questions/widget-testing.md): 18 questions, Mid-Level
- [Build & Deployment](https://sharpskill.dev/en/technologies/flutter/interview-questions/build-deployment.md): 16 questions, Mid-Level
- [Package Management](https://sharpskill.dev/en/technologies/flutter/interview-questions/package-management.md): 16 questions, Mid-Level
- [Memory & Performance](https://sharpskill.dev/en/technologies/flutter/interview-questions/memory-performance.md): 22 questions, Senior
- [Streams & RxDart](https://sharpskill.dev/en/technologies/flutter/interview-questions/streams-rxdart.md): 24 questions, Senior
- [Advanced State Management](https://sharpskill.dev/en/technologies/flutter/interview-questions/advanced-state-management.md): 26 questions, Senior
- [Flutter Design Patterns](https://sharpskill.dev/en/technologies/flutter/interview-questions/flutter-design-patterns.md): 24 questions, Senior
- [Performance Optimization](https://sharpskill.dev/en/technologies/flutter/interview-questions/performance-optimization.md): 26 questions, Senior
- [Platform Channels](https://sharpskill.dev/en/technologies/flutter/interview-questions/platform-channels.md): 20 questions, Senior
- [Custom Painting](https://sharpskill.dev/en/technologies/flutter/interview-questions/custom-painting.md): 22 questions, Senior
- [Flutter Application Architecture](https://sharpskill.dev/en/technologies/flutter/interview-questions/flutter-app-architecture.md): 22 questions, Senior

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