valarray::apply

Applies a specified function to each element of a valarray.

valarray<Type> apply(
   Type _Func(Type)
) const;
valarray<Type> apply(
   Type _Func(const Type&)
) const;

Parameters

• _Func(Type)
  The function object to be applied to each element of the operand valarray.

• _Func(const Type&)
  The function object for const to be applied to each element of the operand valarray.

Return Value

A valarray whose elements have had _Func applied element-wise to the elements of the operand valarray.

Remarks

The member function returns an object of class valarray<Type>, of length size, each of whose elements I is func((*this)[I]).

Example

// valarray_apply.cpp
// compile with: /EHsc
#include <valarray>
#include <iostream>

using namespace std;

int __cdecl MyApplyFunc( int n )
{
   return n*2;
}

int main( int argc, char* argv[] )
{
   valarray<int> vaR(10), vaApplied(10);
   int i;

   for ( i = 0; i < 10; i += 3 )
      vaR[i] = i;

   for ( i = 1; i < 10; i += 3 )
      vaR[i] = 0;

   for ( i = 2; i < 10; i += 3 )
      vaR[i] = -i;

   cout << "The initial Right valarray is: (";
   for   ( i=0; i < 10; ++i )
      cout << " " << vaR[i];
   cout << " )" << endl;

   vaApplied = vaR.apply( MyApplyFunc );

   cout << "The element-by-element result of "
       << "applying MyApplyFunc to vaR is the\nvalarray: ( ";
   for ( i = 0; i < 10; ++i )
      cout << " " << vaApplied[i];
   cout << " )" << endl;
}

The initial Right valarray is: ( 0 0 -2 3 0 -5 6 0 -8 9 )
The element-by-element result of applying MyApplyFunc to vaR is the
valarray: (  0 0 -4 6 0 -10 12 0 -16 18 )

Requirements

Header: <valarray>

Namespace: std

See Also

Concepts

valarray Class

valarray Members