Operations in Dart

    Today, we'll be taking a look at operators in the Dart language. A lot of the operators are things you'd expect from your Algebra class.

Arithmetic Operators 

// addition
print(1 + 2); // will return 3

// subtraction
print(2 - 1); // will return 1

// multiplication
print(2 * 2); // will return 4

// double division
print(5 / 2); // will return 2.5;

// integer division
print(5 ~/ 2); // will return 2;

// modulus
print(5 %2 ); // will return 1;
  • The difference between integer and double division is just the type of the return value.
  • Negative values are supported in these operators.
  • The output is entirely dependent on the operator so even if you did 5.0~/2.0, it would still return 2.
  • Modulus is the remainder from the division operation.

Increment / Decrement Operators

  • If you want a shorthand way to increase or decrease a value, you can use the ++ or -- operators.
  • There are two version of these as well, known as postfix / prefix.
    • Prefix: The value is incremented first, then returned.
    • Postfix: The value is returned, then incremented.
    • Let's take a look at an example to better understand this. 
void main() {
  var a = 0;

  // what do you think the output will be?
  print(increaseNum(a));
}

int increaseNum(int num) {
  return num++;
}
  • The output will be 0, because the function returns the number (which was 0) and then gets increased, but that doesn't matter for this example.
  • However, this example will produce the number we may have wanted. 
void main() {
  var a = 0;

  // will print 1
  print(increaseNum(a));
}

int increaseNum(int num) {
  return ++num;
}
  • There is another way to do a shorthand increment and assignment with += operator. 
void main() {
  var a = 0;

  print(increaseNum(a));
}

int increaseNum(int num) {
  return num += 1;
}
  • This will behave like a prefix increment.
  • In addition to that, you would have benefit of being able to increase by any amount, unlike the ++ operator which limits you to only increase of 1 (or decrease of 1 with --).

Assignment Operators 

// basic assignment operator
var a = 1;

// will print 2
var a = 1;
print(a += 1);

// will print 0
var a = 1;
print(a -= 1);

// will print 1
var a = 1;
print(a *= 1);

// this actually won't compile because we can't assign a double to an int
var a = 1;
print(a /= 1);

// will print 1
var a = 1;
print(a ~/= 1);
  • You might be wondering what exactly an assignment operator is. It is essentially just something that sets the value of what we have on the left side of the = to the value on the right side.

Relational Operators 

// true
print(0 < 1);

// false
print(0 > 1);

// true
print(0 <= 1);

// false
print(0 >= 1);

// true
print(1 == 1);

// true
print(0 != 1);
  • Relational operators evaluate two values on either side of it's operand and return either true or false depending on which it is.

Logical Operators

  • There's 3 logical operators:

    • !
      • This operator toggles the value to the opposite boolean value of what it currently is set to.
    • &&
      • This operator evaluates an expression on both sides and returns true if both sides are true, other wise returns false.
    • ||
      • This operator evaluates an expression on both sides and returns true if one side is true.

  • There are "truth tables" you can look up to get a better understanding of these logical operators. Here's an example of one:

Conclusion

That's about it for operators in Dart. Up next is how to break up flow of logic in your programs utilizing Dart!
If you have any question, leave a comment or reach out to me directly and I'll do my best to help you and / or revise my post for better clarity.

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DartFlutter