I am working on this telephone problem and i need serious help. I am new to C# and this is very difficult for me. I would greatly appreciate in-depth help and guidance.
people sometimes give their telephone numbers using one or more alphabetic characters. Write a program that accepts a 10-digit telephone number that may contain one or more alphabetic characters. Display the corresponding number using numberals. The numbers and letters are associated as follows on your telephone.:
ABC:2
DEF:3
GHI:4
JKL:5
MNO:6
PQRS:7
TUV:8
WXYZ:9
if the user enters a character that is not on the telphone as part of the number, display a message indicating that the value does not match a number. Allow both upper- and lowercase characters to be entered.