Conditions in Dart

Conditions In Dart

When a certain condition is true, you need to execute a certain code. In such situations, you can use conditions in Dart. For E.g, if a student score more than 90 marks then he got grade A.

Types Of Condition

  • If Condition
  • If-Else Condition
  • If-Else-If Condition
  • Switch case

If Condition

It is used when you have to execute statements when certain condition is true.

Syntax

if(condition) {
    Statement 1;
    Statement 2;
       .
       .
    Statement n;
}

Example Of If Condition

It prints whether the person is voter. If the person age is greater and equal to 18, it will print, You are voter.

void main()
{
    var age = 20;
    
    if(age >= 18){
      print("You are voter.");
    }
}
Show Output

If-Else Condition

If the result of the condition is true, then body of if-condition is executed, otherwise body of else-condition will be executed.

Syntax

if(condition){
statements;
}else{
statements;
}

Example Of If-Else Condition

It prints whether the person is voter or not.

  void main()
  {
        int age = 12;
        if(age >= 18){
            print("You are voter.");
        }else{
            print("You are not voter.");
        }
  }
Show Output

If-Else-If Condition

When you have multiple if conditions, then you can use if-else-if. You can learn more in example below.

Syntax

if(condition1){
statements1;
}else if(condition2){
statements2;
}else if(condition3){
statements3;
}
.
.
.
else(conditionN){
statementsN;
}

Example Of If-Else-If Condition

void main() {
  int noOfMonth = 5;

  // Check the no of month
  if (noOfMonth == 1) {
    print("The month is jan");
  } else if (noOfMonth == 2) {
    print("The month is feb");
  } else if (noOfMonth == 3) {
    print("The month is march");
  } else if (noOfMonth == 4) {
    print("The month is april");
  } else if (noOfMonth == 5) {
    print("The month is may");
  } else if (noOfMonth == 6) {
    print("The month is june");
  } else if (noOfMonth == 7) {
    print("The month is july");
  } else if (noOfMonth == 8) {
    print("The month is aug");
  } else if (noOfMonth == 9) {
    print("The month is sep");
  } else if (noOfMonth == 10) {
    print("The month is oct");
  } else if (noOfMonth == 11) {
    print("The month is nov");
  } else if (noOfMonth == 12) {
    print("The month is dec");
  } else {
    print("Invalid option given.");
  }
}
Show Output

Find Greatest Number Among 3 Numbers.

void main()
{
        int num1 = 1200;
        int num2 = 1000;
        int num3 = 150;

        if(num1 > num2  && num1 > num3){
            print("Num 1 is greater: i.e $num1");
        }
        if(num2 > num1 && num2 > num3){
           print("Num2 is greater: i.e $num2");
        }
        if(num3 > num1 && num3 > num2){
            print("Num3 is greater: i.e $num3");
        }
    }
Show Output

Assert

It will take conditions as an argument. If the condition is true, nothing happens. If a condition is false, it will raise an error.

Syntax

assert(condition);
void main() { 
   var age = 22;
   assert(age!=22);
}
Show Output
Info

Note: The assert(condition) method only runs in development mode. It will throw an exception only when the condition is false. If the condition is true, nothing happens. Production code ignores it.