This tutorial shows you how to write a Conditional operator in Dart Programming.

There are two types of conditional Operators in Dart.

  • Ternary Operator
  • Null-coalescing operators

Ternary Operator in Dart example

Ternary operators in the Dart language.

conditional_expression ? statement1 : statement2;

Conditional_expression is a valid dart expression, that evaluates to true or false.

  • statement1: Dart statements to execute if the condition is evaluated to be true.
  • statement2: Dart statements to execute if the condition is evaluated to false.

It is equivalent to following if else syntax.

if (conditional_expression) {
    statement1;
} else {
    statement2;
}

if true, statement1 is executed, else statement2 is executed.

Here is an example

void main(){
   var age = 45;
   age > 60 ? print("Senior Citizen") : print("Not Senior Citizen");
}

Dart Null-coalescing operators examples

Nullish Coalescing Operator is a new feature in Dart and its symbol is ?? i.e. double question mark.

Logical and shortcircuit operator that operates on two operands and returns its value of

  • right-hand operand value when the left-hand operand is null or undefined
  • left-hand operand value when the left-hand operand is not null or undefined

This will be useful for defaulting to a fallback value when object properties are null or undefined.

Syntax:

Left Operand ?? Right Operand

Here is an example

void main(){
  var str=null;
  print(str ?? 'default'); //default

  var str1="one";
  print(str1 ?? 'default'); // one
}