check individual characters on input

hey!
Im a bit stuck on this one, wondered if anyone could help.

I need to perform initial validation of some data entries, on an immidiate character by character basis rather than waiting for an entire line to input then pressing enter.

When the characters have been verified they are then echoed to the screen, but only characters that have been verified.

any ideas anyone??

Its me again if this isnt clear ill try to explain erm.....

if i use
gets(example) i cant evaluate each character untill i have pressed return, then i can do so in the array. I need to be able to evaluate a character as soon as its pressed on the keyboard.

any ideas, im really stuck.

its ok im dumb, ive finally found out getch such a dubass or what? i should read more often!