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The ~ operator is the unary bitwise complement operator. It performs a logical NOT operation on the binary representation of a number, inverting every bit so that each 0 becomes 1 and each 1 becomes 0.

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Syntax

var result = ~expression;

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Type Support

The operator is defined for the following types in the Dart core library:
  • int: Performs bitwise inversion on the platform-specific integer representation.
  • BigInt: Performs bitwise inversion on an arbitrarily large integer.
User-defined classes can support this operation by overloading operator ~().

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Platform Semantics

The bit-width used for the operation depends on the compilation target. Dart Native (VM, Mobile, Desktop) The int type is a 64-bit two’s complement integer. The operator inverts all 64 bits. Dart Web (JavaScript) The int type maps to a JavaScript number (IEEE 754 double-precision float). When the ~ operator is applied:
  1. The operand is truncated to a 32-bit signed integer.
  2. The bits are inverted within this 32-bit range.
  3. The result is a 32-bit signed integer.
Note: Because of this truncation, applying ~ to an integer larger than 32 bits on the web will result in data loss before the inversion occurs.

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Mathematical Relationship

For integers using two’s complement representation, the relationship between the effective operand xx and the result is defined by the following formula: ∼x=(−x)−1\sim x = (-x) - 1 On Dart Web, this formula applies to the truncated 32-bit value, not necessarily the original operand if it exceeds 32 bits.
Operand (xx)Binary RepresentationComplement (∼x\sim x)Result Decimal
0...0000...1111-1
1...0001...1110-2
-1...1111...00000

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Binary Visualization

The following example demonstrates the inversion of the integer 5 (binary ...0000 0101). 
void main() {
  int x = 5;
  
  // Binary of 5:  ...0000 0101
  // Inverted:     ...1111 1010
  // Result is -6 in two's complement
  
  int result = ~x;

  print(result); // Output: -6
}
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