How to check for invalid input

#1

how to check for invalid input

#2

hi…

#3

if user does not gives the UPPERCASE or lowercase
then you have to print “invalid”

you can do this by simply using
"if else " ladder

i hope this helps,
if you have further doubt, feel free to ask

#4

reference code :

#5

hellooooooooooooooooooooo

#6

do you have any further doubt in this?