Conditional Expressions and Null-Aware Operators
Conditional expressions and null-aware operators in Dart provide powerful ways to write concise, readable code when handling decisions and optional values. The ternary operator allows you to choose between two expressions based on a condition, replacing simple if-else statements with a single line. Meanwhile, null-aware operators such as ??, ??=, ?., and ! help you safely work with variables that might be null, making it easier to provide defaults or avoid runtime errors when dealing with optional data.
main.dart
12345void main() { bool isLoggedIn = true; String statusMessage = isLoggedIn ? 'Welcome back!' : 'Please log in.'; print(statusMessage); }
In the code above, the ternary operator checks the value of isLoggedIn. If isLoggedIn is true, statusMessage is set to "Welcome back!"; otherwise, it is set to "Please log in.". This one-liner replaces a longer if-else block, making your code shorter and easier to read. The general syntax is condition ? valueIfTrue : valueIfFalse;, which is ideal for straightforward decisions where only two outcomes are possible.
main.dart
12345void main() { String? userInput; String name = userInput ?? 'Guest'; print('Hello, $name!'); }
Null-aware operators like ?? help you provide a fallback value when a variable might be null. In the previous example, userInput is declared as a nullable String. If userInput is null, the name variable is assigned "Guest" instead. This approach prevents null errors and eliminates the need for extra if statements. Using null-aware operators makes your code more robust and easier to maintain, especially when handling optional or user-provided data.
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Can you give more examples of using the ternary operator in Dart?
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Conditional expressions and null-aware operators in Dart provide powerful ways to write concise, readable code when handling decisions and optional values. The ternary operator allows you to choose between two expressions based on a condition, replacing simple if-else statements with a single line. Meanwhile, null-aware operators such as ??, ??=, ?., and ! help you safely work with variables that might be null, making it easier to provide defaults or avoid runtime errors when dealing with optional data.
main.dart
12345void main() { bool isLoggedIn = true; String statusMessage = isLoggedIn ? 'Welcome back!' : 'Please log in.'; print(statusMessage); }
In the code above, the ternary operator checks the value of isLoggedIn. If isLoggedIn is true, statusMessage is set to "Welcome back!"; otherwise, it is set to "Please log in.". This one-liner replaces a longer if-else block, making your code shorter and easier to read. The general syntax is condition ? valueIfTrue : valueIfFalse;, which is ideal for straightforward decisions where only two outcomes are possible.
main.dart
12345void main() { String? userInput; String name = userInput ?? 'Guest'; print('Hello, $name!'); }
Null-aware operators like ?? help you provide a fallback value when a variable might be null. In the previous example, userInput is declared as a nullable String. If userInput is null, the name variable is assigned "Guest" instead. This approach prevents null errors and eliminates the need for extra if statements. Using null-aware operators makes your code more robust and easier to maintain, especially when handling optional or user-provided data.
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