contraire de string.Split

Bonjour
y a til une fonction qui fasse le contraire de string[] tabCh = ch1.Split ?

en fait j'ai un tableau de string que je voudrais mettre dans une chaine
tab[1] = "a"
tab[2] = "b"
tab[3] = "c"
===> string chResult = "a - b - c"

Merci
DT

HI Everyone,

i'm not really in computers but i'm trying to learn !!! in fact i'm taking a computer class  on visual C# .NET 2003 and i need help on two topics if you don't mind (Thanks in advance)

Topic : Returning Date from a Custom Method to a Decision

use a custom method to return the First letter of the last name as a Char data Type. use this returned data in a decision type to send the student/user a MessageBox telling them wich room to go to for registration.
example: if the student's last name begins with 'A' through 'H' then send the student to room 1
and if student's last name begins with 'I' through 'S' send to room 2

What i need is the codes, i did the form already. thanks a lot