< cpp‎ | numeric‎ | valarray
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valarray<T> apply( T func(T) ) const;
valarray<T> apply( T func(const T&) ) const;

Returns a new valarray of the same size with values which are acquired by applying function func to the previous values of the elements.


[edit] Parameters

func - function to apply to the values

[edit] Return value

The resulting valarray with values acquired by applying function func.

[edit] Notes

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++14) 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.

[edit] Example

calculates and prints the first 10 factorials

#include <iostream>
#include <valarray>
#include <cmath>
int main()
    std::valarray<int> v = {1,2,3,4,5,6,7,8,9,10};
    v = v.apply([](int n)->int {
                    return std::round(std::tgamma(n+1));
    for(auto n : v) {
        std::cout << n << ' ';
    std::cout << '\n';


1 2 6 24 120 720 5040 40320 362880 3628800

[edit] See also

applies a function to a range of elements
(function template) [edit]