# [Flutter] Operator in Dart

2021-04-01 ## Blog series

This blog post is a series. You can see the other posts on the link below.

## Outline

Let’s see what operators are in Dart and how to use them.

You can see the source code, that is introduced on this blog post, on the link below

## Arithmetic operators

When you calculate the numbers, you can use the arithmetic operators like other languages.

``````void main() {
double num1 = 4;

print(num1 + 2);
print(num1 - 2);
print(num1 * 2);
print(num1 / 2);
print(num1 % 3);
print(num1++);
print(num1--);
print(++num1);
print(--num1);
print(num1 += 1);
print(num1 -= 1);
print(num1 *= 1);
print(num1 /= 2);
print(num1 %= 3);
}
``````

## Comparison operators

You can use the Comparison operators in Dart like other langauges.

``````void main() {
int num1 = 3;
int num2 = 5;

print(num1 > num2);
print(num1 < num2);
print(num1 >= num2);
print(num1 <= num2);
print(num1 == num2);
print(num1 != num2);
}
``````

## Type comparison operators

You can compare the Type of the variable like below.

``````void main() {
int num = 3;

print(num is int);
print(num is String);
print(num is List);
}
``````

You can check that the types are not the same as follows.

``````void main() {
int num = 3;

print(num is! int);
print(num is! String);
print(num is! List);
}
``````

## Logical operators

You can use the logical operators in Dart like other langauges.

``````void main() {
print(true && true);
print(true && false);
print(false && true);
print(false && false);
print(true || true);
print(true || false);
print(false || true);
print(false || false);
}
``````

## Null-aware operator

You can use `??=` operator in Dart. This operator assigns the value only when the variable is `null`.

``````void main() {
var name = null;
name ??= 'Yakuza';
print(name);

name ??= 'Dev';
print(name);
}
``````

The `name` varialbe is not initialized, so it is assinged `null`. First `??=` operator can assign the value because the `name` is `null`, but second `??=` operator doesn’t assign because the variable is not `null`.

## Completed

We’ve seen what operators are in Dart and how to use the operators. We’ve known that we can use the almost operators of the other languages in Dart.

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