From cppreference.com
valarray(); (1) explicitvalarray(std::size_tcount); (2) valarray(constT&val,std::size_tcount); (3) valarray(constT*vals,std::size_tcount); (4) valarray(constvalarray&other); (5) valarray(valarray&&other)noexcept; (6) (since C++11)valarray(conststd::slice_array<T>&sa); (7) valarray(conststd::gslice_array<T>&gsa); (8) valarray(conststd::mask_array<T>&ma); (9) valarray(conststd::indirect_array<T>&ia); (10) valarray(std::initializer_list<T>il); (11) (since C++11)Constructs new numeric array from various sources.
1) Default constructor. Constructs an empty numeric array.
2) Constructs a numeric array with count copies of
elements.
3) Constructs a numeric array with count copies of val.
4) Constructs a numeric array with copies of count values from an array pointed to by vals. If this array contains less than count values, the behavior is undefined.
5) Copy constructor. Constructs the numeric array with the copy of the contents of other.
6) Move constructor. Constructs the container with the contents of other using move semantics.
11) Constructs the numeric array with the contents of the initializer list il.
Parameters
count - the number of elements to construct val - the value to initialize the elements with vals - pointer to a C array to use as source to initialize the contents other - another numeric array to use as source to initialize the contents sa - slice array to initialize the elements with gsa - generic slice array to initialize the elements with ma - mask array to initialize the elements with ia - indirect array to initialize the elements with il - initializer list to initialize the elements with Exceptions
1-5, 7-11) May throw implementation-defined exceptions.
Example