We can prevent duplicate data from entering into the array, by checking the contents of the array. This program makes an array of first names. When the user enters a first name the program goes through the array checking each name. If the name is found in the array then the program prompts the user for another name. If the name is not found then the program allows the name to go into the array.
Code Download
QBT21.BAS
QB64 is a free download at www.qb64.com
QB64 Wiki & Manual is found at qb64.com/wiki.html
QBasic 1.1 comes with OldDOS. A zip file of OldDOS can be found at www.pcxt-micro.com/download.html
QBasic 1.1 needs DOSBox to run on Windows Vista and greater, Mac, and Linux.
DosBox is a free download at www.dosbox.com
Free QB64/QBasic Code
QBasic.Net - www.qbasic.net
Pete's QBasic Site - www.petesqbsite.com/index.php
QB45 - qb45.org
Phatcode - games.phatcode.net