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:

• All const member functions of std::valarray are provided.
• std::valarray, std::slice_array, std::gslice_array, std::mask_array and std::indirect_array can be constructed from the replacement type.
• For every function taking a const std::valarray<T>& except begin() and end()(since C++11), identical functions taking the replacement types shall be added;
• For every function taking two const std::valarray<T>& arguments, identical functions taking every combination of const std::valarray<T>& and replacement types shall be added.
• The return type does not add more than two levels of template nesting over the most deeply-nested argument type.

Example

#include <iostream>
#include <string_view>
#include <valarray>

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);
}

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