std::valarray::operator+,-,~,! - cppreference.com (original) (raw)

| 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.

[edit] Parameters

(none)

[edit] Return value

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

[edit] Exceptions

May throw implementation-defined exceptions.

[edit] 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.

[edit] Example

#include #include #include template void print(std::string_view const note, std::valarray 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 x{1, 2, 3, 4}; print("x: ", x); print("+x: ", +x); print("+ + x: ", + + x); print("-x: ", -x); print("- - x: ", - - x, "\n\n"); std::valarray y{0, 1, -1, 0x7fff}; print("y: ", y); print("~y: ", ~y); print("~~y: ", ~~y, "\n\n"); std::valarray z{true, false}; print("z: ", z); print("!z: ", !z); print("!!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