Operators

The Boolean NOT operator, AKA logical NOT operator, is a unary prefix operator, which chages a Boolean true to false, and a Boolean false to true.

boolean-not-operator

!: int × int

!: long × long

!: unsigned int × unsigned int

!: unsigned long × unsigned long

boolean-not-operator

1. The operand is evaluated.
2. if the operand value is integral, but smaller than an int, it is coerced (widened) to an int.
3. A value of 0 is interpredted as false.
4. Any value not 0 is interpredted as true.
5. The result is the Boolean NOT of the interpreted value:

   Boolean NOT
   Operand	Result
   0	1
   1	0

6. I.E., the result is 1 if the operand is 0, and the result is 0 if the operand is not 0.

• The Boolean NOT operator is not supported for floating point operands.

#include <stdio.h>

void LogicalNot (int A);

int main () {
  LogicalNot (0);
  LogicalNot (1);
  LogicalNot (-1);
  LogicalNot (15);
  return 0;
}

void LogicalNot (int A) {
  printf ("! %i = %i\n", A, (! A));
}

! 0 = 1
! 1 = 0
! -1 = 0
! 15 = 0