Simple Number Scanner
void number (TOKEN tok)
{ long num;
int c, charval;
num = 0;
while ( (c = peekchar()) != EOF
CHARCLASS[c] == NUMERIC)
{ c = getchar();
charval = (c - '0');
num = num * 10 + charval;
}
tok-> tokentype = NUMBERTOK;
tok-> datatype = INTEGER;
tok-> intval = num;
}