Conditional expression in Dart :

Conditional expressions are used in place of if-else statements. These expressions are short, concise and easy to understand.

Two different types of conditional expressions are available in dart. In this post, I will show you both of these expressions with examples.

Conditional expression definition :

Following are the definitions of the conditional expressions :

condition ? first_expression : second_expression

and,

first_expression ?? second_expression

Explanation :

The first expression checks the condition first. If it is true, it executes the first_expression, else, it executes the second_expression.

If we write the first one using if-else, it looks like as below :

if(condition){
    return first_expression;
}else{
    return second_expression;
}

The second expression checks for null of the first_expression. If it is null, it executes the second_expression. if-else syntax for this expression is like below :

if(first_expression != null){
    return first_expression;
}else{
    return second_expression;
}

Example 1: Find out the larger number using conditional expression :

Let’s write one program to find the larger number using conditional expression. If you use if-else, it will be like below :

main() {
  int num1 = 10;
  int num2 = 9;

  int largerNum;

  if (num1 > num2) {
    largerNum = num1;
  } else {
    largerNum = num2;
  }
  print(largerNum);
}

Using conditional expression :

main() {
  int num1 = 10;
  int num2 = 9;

  int largerNum = num1 > num2 ? num1 : num2;

  print(largerNum);
}

Both programs will print 10 as the output.

Example 2 : Check null using conditional expression :

main() {
  String str1 = null;
  String str2 = "str1 is null";

  String result = str1 ?? str2;
  print(result);
}

This example will print “str1 is null”. Because the value of str1 is null. So, it will assign str2 to result.