std::valarray<T>::cshift
From cppreference.com
valarray<T> cshift( int count ) const;
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Returns a new valarray of the same size with elements whose positions are shifted circularly by count elements.
A non-negative value of count shifts the elements circularly left count places and a negative value of count shifts the elements circularly right -count places.
Parameters
| count | - | number of positions to shift the elements by |
Return value
The resulting valarray with circularly shifted elements.
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
constmember 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 ofconst 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
Run this code
#include <print>
#include <valarray>
int main()
{
const std::valarray<int> v{1, 2, 3, 4, 5, 6, 7, 8};
std::println("{}", v);
std::println("{} <- 3", v.cshift(3));
std::println("{} <- 11", v.cshift(11));
std::println("{} -> 2", v.cshift(-2));
std::println("{} -> 10", v.cshift(-10));
}
Output:
[1, 2, 3, 4, 5, 6, 7, 8]
[4, 5, 6, 7, 8, 1, 2, 3] <- 3
[4, 5, 6, 7, 8, 1, 2, 3] <- 11
[7, 8, 1, 2, 3, 4, 5, 6] -> 2
[7, 8, 1, 2, 3, 4, 5, 6] -> 10
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 618 | C++98 | the expression of the shifted elements contains zero-division if size() is 0
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describes the new positions without using expressions |
See also
| zero-filling shift the elements of the valarray (public member function) |