Every 2 Letter Combo for Array of Strings

[sloan]

string[] array = new string[3] {"A","B","C" };


Given the above data, I'm trying to find C# code which will produce




A,A
B,A
C,A
A,B
B,B
C,B
A,C
B,C
C,C


Its been a long week, and I'm brain dead, and googled out.


Thanks for any help.

[Marc Gravell]

Re: Every 2 Letter Combo for Array of Strings

Erm, loop?

string[] array = { "A", "B", "C" };
for(int i = 0; i < array.Length; i++)
for (int j = 0; j < array.Length; j++)
{
Console.WriteLi ne("{0},{1}", array[j], array[i]);
}

You could do something more exciting, but that should do...

Marc

[sloan]

Re: Every 2 Letter Combo for Array of Strings

Like I said dude....brain dead.


"Marc Gravell" <marc.gravell@g mail.comwrote in message
news:7981a025-7a58-43f1-b260-5f457fd5f10a@v4 g2000hsf.google groups.com...

Erm, loop?
>
string[] array = { "A", "B", "C" };
for(int i = 0; i < array.Length; i++)
for (int j = 0; j < array.Length; j++)
{
Console.WriteLi ne("{0},{1}", array[j], array[i]);
}
>
You could do something more exciting, but that should do...
>
Marc

[Nicholas Paldino [.NET/C# MVP]]

Re: Every 2 Letter Combo for Array of Strings

Something more exciting being (if the OP is using .NET 3.5/C# 3.0):

string[] array = { "A", "B", "C" };

IEnumerable<str ingquery =
from a in array
from b in array
select a + "," + b // Could be string.Format(" {0},{1}", a, b) as well if
you wish.

foreach (string item in query)
{
Console.WriteLi ne(item);
}

--
- Nicholas Paldino [.NET/C# MVP]
- mvp@spam.guard. caspershouse.co m


"Marc Gravell" <marc.gravell@g mail.comwrote in message
news:7981a025-7a58-43f1-b260-5f457fd5f10a@v4 g2000hsf.google groups.com...

Erm, loop?
>
string[] array = { "A", "B", "C" };
for(int i = 0; i < array.Length; i++)
for (int j = 0; j < array.Length; j++)
{
Console.WriteLi ne("{0},{1}", array[j], array[i]);
}
>
You could do something more exciting, but that should do...
>
Marc

[Marc Gravell]

Re: Every 2 Letter Combo for Array of Strings

Like I said dude....brain dead.

I know that feeling;-p

Currently in "crunch"; I don't expect to be getting to sleep any time
soon...

Marc

[Marc Gravell]

Re: Every 2 Letter Combo for Array of Strings

(laughs)

I actually deliberately stopped myself posting the LINQ version, aware
(over-cautious) that LINQ isn't yet fully mainstream... oh well ;-p

Marc

[Marc Gravell]

Re: Every 2 Letter Combo for Array of Strings

IEnumerable<str ingquery =

    ...
    select new { A1Label = a, A2Label = b, NotSame = (a != b) };

(minor; just for the OP really) - you'd need "var query" here because
of the anonymous type in the projection

Marc

[Jeroen Mostert]

Re: Every 2 Letter Combo for Array of Strings

Nicholas Paldino [.NET/C# MVP] wrote:

Well, in SQL, you don't have to explicitly state CROSS JOIN anymore (and
I do believe it is actually not recommended now, but I'd have to look that
up), you can just do:
>
select
a1.AlphabetLabe l as A1Label, a2.AlphabetLabe l as A2Label,
case a1.AlphabetLabe l when a2.AlphabetLabe l then 0 else 1 end as NotSame
from
Alphabet as a1, Alphabet as a2
>

CROSS JOIN was introduced in SQL-92 to solve some ambiguity problems with
the comma notation and increase clarity (before this you couldn't use them,
so it's not a case of "not having to state it anymore"; the comma notation
came first). I'm not aware of any explicit recommendation for or against,
and either syntax will work fine.

However, it's still a very good idea to write out the CROSS JOIN explicitly,
since it's the most uncommon form of join (even if it's the most natural
one, mathematically speaking) and alerting your fellow developer to its use
is a good idea. An "accidental " cross join is not a good thing to have (as
even moderately-sized tables will produce enormous result sets) which is
exactly why ANSI SQL introduced explicit syntax for them.

--
J.

[Marc Gravell]

Re: Every 2 Letter Combo for Array of Strings

that'd better not be a ghost-busters joke!