Web Forms :: Loop Through The Alphabet Depends On The Length?

i want write a coding to loop through the alphabet depends on the length.

Below is the condition i want:

total_display_all = "2,10,4,25,17" 'length = 5
Dim I_total()
As
String = total_display_all.Split(",")
Dim alphabet = string
Dim alphabet_all = string
For i = 0
To I_total.Length - 1

alphabet_all = alphabet 'don't know how to write this part of codingNext

final output i want:

when length = 5, alphabet = "A,B,C,D,E"
when length = 2, alphabet ="A,B"
when length = 10, alphabet = "A,B,C,D,E,F,G,H,I,J"

the alphabet depends on the length of total_display_all.

i don't know how to write the coding to loop through alphabet.