Matrix Keypad - Optimisation

if i understand this right, I could redefine keypressed as char long and then use the actual names for the keys, ie 0 -9 a b c d menu enter, instead of 1-16

then when writing the code for the different cases I don't mix up which key I'm actually pressing

Another question can I nest case statements?

ie

switch(keypressed){
case menu:
//display options

switch (keypressed){
case a:
//do a
break;

case b:
//do b
break;

case c:
//do c
break;

case d:
//do d
break;
}
break;

case xx:
//continue other cases

and then continue primary case commands for other keys

thanks again,

Carl