Assignment Operators

Learn how to assign and modify variable values using assignment operators in Dart

Overview

Assignment operators are used to assign values to variables. Dart provides compound assignment operators that combine arithmetic operations with assignment, making your code more concise.

Assignment Operators Table

Operator	Description	Example	Equivalent To
=	Simple assignment	x = 5	-
+=	Add and assign	x += 5	x = x + 5
-=	Subtract and assign	x -= 3	x = x - 3
*=	Multiply and assign	x *= 2	x = x * 2
/=	Divide and assign	x /= 4	x = x / 4
~/=	Integer divide and assign	x ~/= 4	x = x ~/ 4
%=	Modulo and assign	x %= 3	x = x % 3

Basic Example

Here’s a complete example showing how assignment operators work:

void main() {
  //Operadores de Asignación
  int numero = 17;
  print(numero);

  numero += 5;    // numero = numero + 5  → numero = 15
  print(numero);
  numero -= 3;    // numero = numero - 3  → numero = 12
  print(numero);
  numero *= 2;    // numero = numero * 2  → numero = 24
  print(numero);
  numero ~/= 4;   // numero = numero ~/ 4 → numero = 6
  print(numero);
}

Output:

17
22
19
38
9

The comment in the original code has calculation errors, but the actual execution follows the correct logic: 17 + 5 = 22, 22 - 3 = 19, 19 * 2 = 38, 38 ~/ 4 = 9.

Why Use Compound Operators?

Compound assignment operators make your code:

• More concise: Less typing required
• More readable: Clear intent to modify a variable
• Less error-prone: You don’t repeat the variable name

Comparison

// Without compound operator
int counter = 10;
counter = counter + 1;  // Longer, repetitive

// With compound operator
int counter = 10;
counter += 1;  // Shorter, clearer

For incrementing or decrementing by 1, Dart also provides ++ and -- operators:

• counter++ is equivalent to counter += 1
• counter-- is equivalent to counter -= 1

Practical Examples

Accumulating Values

int total = 0;
total += 10;  // Add 10 to total
total += 20;  // Add 20 more
total += 5;   // Add 5 more
print(total); // Output: 35

Updating Calculations

double price = 100.0;
price *= 1.15;    // Apply 15% tax
price -= 10.0;    // Apply $10 discount
print(price);     // Output: 105.0

Integer Division Assignment

int items = 50;
items ~/= 3;      // Divide into groups of 3
print(items);     // Output: 16 (complete groups)