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valarray::operator~ 

A unary operator that obtains the bitwise NOT values of each element in a valarray.


valarray<Type> operator~( ) const;

The valarray of Boolean values that are the bitwise NOT of the element values of the operand valarray.

A bitwise operation can only be used to manipulate bits in char and int data types and variants and not on float, double, long double, void, bool or other, more complex data types.

The bitwise NOT has the same truth table as the logical NOT but applies to the data type on the level of the individual bits. Given bit b, ~b is true if b is false and false if b is true. The logical NOT operator! applies on an element level, counting all nonzero values as true, and the result is a valarray of Boolean values. The bitwise NOT operator~, by contrast, can result in a valarray of values other than 0 or 1, depending on outcome of the bitwise operation.

// valarray_op_bitnot.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   valarray<unsigned short int> vaL1 ( 10 );
   valarray<unsigned short int> vaNOT1 ( 10 );
   for ( i = 0 ; i < 10 ; i += 2 )
      vaL1 [ i ] =  i;
   for ( i = 1 ; i < 10 ; i += 2 )
      vaL1 [ i ] =  5*i;
   
   cout << "The initial valarray <unsigned short int> is:  ( ";
      for ( i = 0 ; i < 10 ; i++ )
         cout << vaL1 [ i ] << " ";
   cout << ")." << endl;

   vaNOT1 = ~vaL1;
   cout << "The element-by-element result of "
        << "the bitwise NOT operator~ is the\n valarray: ( ";
      for ( i = 0 ; i < 10 ; i++ )
         cout << vaNOT1 [ i ] << " ";
   cout << ")." << endl << endl;

   valarray<int> vaL2 ( 10 );
   valarray<int> vaNOT2 ( 10 );
   for ( i = 0 ; i < 10 ; i += 2 )
      vaL2 [ i ] =  i;
   for ( i = 1 ; i < 10 ; i += 2 )
      vaL2 [ i ] =  -2 * i;
   
   cout << "The initial valarray <int> is:  ( ";
      for ( i = 0 ; i < 10 ; i++ )
         cout << vaL2 [ i ] << " ";
   cout << ")." << endl;

   vaNOT2 = ~vaL2;
   cout << "The element-by-element result of "
        << "the bitwise NOT operator~ is the\n valarray: ( ";
      for ( i = 0 ; i < 10 ; i++ )
         cout << vaNOT2 [ i ] << " ";
   cout << ")." << endl;

   // The negative numbers are represented using
   // the two's complement approach, so adding one
   // to the flipped bits returns the negative elements
   vaNOT2 = vaNOT2 + 1;
   cout << "The element-by-element result of "
        << "adding one\n is the negative of the "
        << "original elements the\n valarray: ( ";
      for ( i = 0 ; i < 10 ; i++ )
         cout << vaNOT2 [ i ] << " ";
   cout << ")." << endl;
}

Output

The initial valarray <unsigned short int> is:  ( 0 5 2 15 4 25 6 35 8 45 ).
The element-by-element result of the bitwise NOT operator~ is the
 valarray: ( 65535 65530 65533 65520 65531 65510 65529 65500 65527 65490 ).

The initial valarray <int> is:  ( 0 -2 2 -6 4 -10 6 -14 8 -18 ).
The element-by-element result of the bitwise NOT operator~ is the
 valarray: ( -1 1 -3 5 -5 9 -7 13 -9 17 ).
The element-by-element result of adding one
 is the negative of the original elements the
 valarray: ( 0 2 -2 6 -4 10 -6 14 -8 18 ).

Header: <valarray>

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