std::valarray<T>::operator+,-,~,!

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< cpp‎ | numeric‎ | valarray
 
 
 
 
valarray<T> operator+() const;
(1)
valarray<T> operator-() const;
(2)
valarray<T> operator~() const;
(3)
valarray<bool> operator!() const;
(4)

Applies unary operators to each element in the numeric array.

Parameters

(none)

Return value

A numeric array containing elements with values obtained by applying corresponding operator to the values in *this.

Exceptions

May throw implementation-defined exceptions.

Notes

Each of the operators can only be instantiated if the following requirements are met:

  • The indicated operator can be applied to type T
  • The result value can be unambiguously converted to T (1-3) or bool (4).

The function can be implemented with the return type different from std::valarray. In this case, the replacement type has the following properties:

Example

#include <iostream>
#include <valarray>
#include <string_view>
 
template <typename T>
void print(std::string_view const note,
           std::valarray<T> const vala, // by-value, see Notes above
           std::string_view const term = "\n")
{
    std::cout << note << std::boolalpha << std::showpos;
    for (T const element: vala)
        std::cout << '\t' << element;
    std::cout << term;
}
 
int main()
{
    std::valarray<int> x{ 1, 2, 3, 4 };
    print<int>("x: ", x);
    print<int>("+x: ", +x);
    print<int>("+ + x: ", + + x);
    print<int>("-x: ", -x);
    print<int>("- - x: ", - - x, "\n\n");
 
    std::valarray<short> y{ 0, 1, -1, 0x7fff };
    print<short>("y: ", y);
    print<short>("~y: ", ~y);
    print<short>("~~y: ", ~~y, "\n\n");
 
    std::valarray<bool> z{ true, false };
    print<bool>("z: ", z);
    print<bool>("!z: ", !z);
    print<bool>("!!z: ", !!z);
}

Possible output:

x:      +1      +2      +3      +4
+x:     +1      +2      +3      +4
+ + x:  +1      +2      +3      +4
-x:     -1      -2      -3      -4
- - x:  +1      +2      +3      +4
 
y:      +0      +1      -1      +32767
~y:     -1      -2      +0      -32768
~~y:    +0      +1      -1      +32767
 
z:      true    false
!z:     false   true
!!z:    true    false

See also

applies compound assignment operator to each element of the valarray
(public member function)
applies binary operators to each element of two valarrays, or a valarray and a value
(function template)