How can I tell if the code entered in the textbox is in the list txt?

[Carlos_Andre]

I have a list of codes in TXT.
How can I tell if the code entered in the textbox is in the list?
List example:
789456123
789520123
000693
000321
000452

[Still-learning (1-2-3-4...)]

Put all the codes into a list.
Either on text changed or button pressed event just use
is in list thing (textbox text) list(variable)