function call as a 'case' arguement

is it possible to use a function call as a case argument in a switch statement?

Ex.

switch (ch) {
case isdigit(ch): /* runtime error 'not a constant' */
state = FRACTIONAL;
case ' ':
return (2);
case 'E':
state = EXPONENT;
case 'e':
state = EXPONENT;
case 'F':
state = FLOAT;
default:
return(0);
}

> case isdigit(ch): /* runtime error 'not a constant' */
And that's what it means

case labels are integer compile time constants

You could do
case 0:
case 1:
case 2:
case 3:
..
case 9:
state = FRACTIONAL;
break;

That works. Thanks.