logical_not Struct
The struct provides a predefined function object that performs the logical operation of negation on elements of a specified value type and tests for the truth or falsity of the result.
template<class Type>
struct logical_not : public unary_function<Type, bool>
{
bool operator()(
const Type& _Left
) const;
};
Parameters
- _Left
The operand of type Type in the negation to be tested.
Return Value
true if and only if _Left is false; false if and only if _Left is true.
Example
// functional_logical_not.cpp
// compile with: /EHsc
#include <deque>
#include <algorithm>
#include <functional>
#include <iostream>
int main( )
{
using namespace std;
deque<bool> d1, d2 ( 7 );
deque<bool>::iterator iter1, iter2;
int i;
for ( i = 0 ; i < 7 ; i++ )
{
d1.push_back((bool)((i % 2) != 0));
}
cout << boolalpha; // boolalpha I/O flag on
cout << "Original deque:\n d1 = ( " ;
for ( iter1 = d1.begin( ) ; iter1 != d1.end( ) ; iter1++ )
cout << *iter1 << " ";
cout << ")" << endl;
// To flip all the truth values of the elements,
// use the logical_not function object
transform( d1.begin( ), d1.end( ), d2.begin( ),logical_not<bool>( ) );
cout << "The deque with its values negated is:\n d2 = ( " ;
for ( iter2 = d2.begin( ) ; iter2 != d2.end( ) ; iter2++ )
cout << *iter2 << " ";
cout << ")" << endl;
}
Original deque: d1 = ( false true false true false true false ) The deque with its values negated is: d2 = ( true false true false true false true )
Requirements
Header: <functional>
Namespace: std
See Also
Reference
Thread Safety in the Standard C++ Library