NAME

std::valarray::operator+,-,~,! - std::valarray::operator+,-,~,!

Synopsis

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:

* 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.
* All functions accepting an argument of type const std::valarray&
except begin() and end()
(since C++11) should also accept the replacement type.
* All functions accepting two arguments of type const std::valarray&
should accept every combination of const std::valarray& and the
replacement type.
* The return type does not add more than two levels of template nesting
over the most deeply-nested argument type.

Example

// Run this code

#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