I've got some variables that have to be filled in in a form. Now I want to check the correctness of the filled in variables, by checking them on having :
a) both numbers and alphabetic writing
b) numbers only
c) alphabetic writing only
d) a @ character
I do not want certain input to be filled in at certain questions of the form (I want to exclude certain combinations of characters at some questions). Can you provide me with the lines to check the correctness of the variables filled in ?