Converting a IEnumberable sequence into an array - an example here

[raylopez99]

Here is a short program demonstrating using IEnumberable, Linq,
predicates, extension methods and some tricks and how to convert an
IEnumberable sequence into an array.

For future reference, not intended as a question.

RL

Main():
int[] numbers = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,11};

foreach (int i in numbers)
{ Console.Write(" {0} ", i); }

Console.WriteLi ne("");


double average_numbers _here = numbers.Average (); //
extension method

Console.WriteLi ne("average numbers: {0}",
average_numbers _here);

int[] numbers2;
Predicate<intis Aeven = (delegate(int x) { return x % 2 ==
0; });
Console.WriteLi ne("Even(t)?: {0}, Even(f)?: {1}",
isAeven(numbers[0]), isAeven(numbers[1])); //predicate logic

IEnumerable<int numbers3 = numbers.Reverse (); //key, must
defined IEnumerable as such, not really an array but can be made into
one see **&&** below, thus int[] WillNotWorkArra y =
numbers.Reverse (); //will not work directly, but you must do **&&**
below

Console.WriteLi ne("reverse");
foreach (int i3 in numbers3)
{
Console.Write(" {0} ", i3);
}
numbers3 = numbers3.Revers e(); //works fine
Console.WriteLi ne("\n Re-reverse");
foreach (int i32 in numbers3)
{
Console.Write(" {0} ", i32);
}

numbers3 = numbers3.Revers e().Where(n =n % 2 == 0); //
reverse and use even ints only

int ACountVar_of_nu mbers3IEnumbera ble = numbers3.Count( ); //
store # of elements of numbers3 IEnumberable sequence
int ACountV = ACountVar_of_nu mbers3IEnumbera ble; //shorten
the variable name

int[] arrayNumbers3 = new int[ACountV];

int arrayNumbers3_i nt = 0;
Console.WriteLi ne("\n ...");
foreach (int jfill in numbers3)
{
arrayNumbers3[arrayNumbers3_i nt] = jfill; //**&&**
arrayNumbers3_i nt++;
}


for (int ie = 0; ie < ACountV; ie++)
{
Console.Write(" !: {0},", arrayNumbers3[ie]);

}

Console.WriteLi ne("\n Even only, reversed again");
foreach (int i32 in numbers3)
{
Console.Write(" {0} ", i32);
}

Console.WriteLi ne("count is: {0}",
ACountVar_of_nu mbers3IEnumbera ble);

Output:
0 1 2 3 4 5 6 7 8 9 10 11
average numbers: 5.5
Even(t)?: True, Even(f)?: False
reverse
11 10 9 8 7 6 5 4 3 2 1 0
Re-reverse
0 1 2 3 4 5 6 7 8 9 10 11
...
!: 10, !: 8, !: 6, !: 4, !: 2, !: 0,
Even only, reversed again
10 8 6 4 2 0 count is: 6
Press any key to continue . .

[Peter Morris]

Re: Converting a IEnumberable sequence into an array - an example here

int[] numbers2;

Predicate<intis Aeven = (delegate(int x) { return x % 2 ==
0; });

Instead of:
Predicate<intis Aeven = (delegate(int x) { return x % 2 == 0; });

You could:
Predicate<intis Aeven = i =i % 2 == 0;


I am a little annoyed that I can do this

List<intnumbers = ............;
numbers.ForEach (.........);

but I cannot do this

int[] numbers = ............... ....;
numbers.ForEach (.......);

Can anyone tell me why this is? I don't mean why I can't do it, I mean why
it may have been decided to implement in such a way that I can't.



--
Pete
====

http://mrpmorris.blogspot.com

http://www.capableobjects.com

[Jeroen Mostert]

Re: Converting a IEnumberable sequence into an array - an examplehere

Peter Morris wrote:

> int[] numbers2;
> Predicate<intis Aeven = (delegate(int x) { return x % 2 ==
>0; });

>
Instead of:
Predicate<intis Aeven = (delegate(int x) { return x % 2 == 0; });
>
You could:
Predicate<intis Aeven = i =i % 2 == 0;
>
>
I am a little annoyed that I can do this
>
List<intnumbers = ............;
numbers.ForEach (.........);
>
but I cannot do this
>
int[] numbers = ............... ....;
numbers.ForEach (.......);
>
Can anyone tell me why this is? I don't mean why I can't do it, I mean
why it may have been decided to implement in such a way that I can't.
>

Most operations on arrays take the form of static methods of Array,
..ForEach() is no exception. Arrays are special that way.

In any case, Array.ForEach() and List<T>.ForEach () existed before LINQ. If
you ask me they're pretty much useless, since they're no clearer than a
foreach statement. Maybe if your language doesn't support foreach, but
otherwise the only appeal is turning three lines into one -- and you could
actually do that with the foreach statement too.

--
J.