The next program counts the words in a file. K&P define a word as "a sequence of any characters except blanks, tabs and newlines." Since we are not using the NEWLINE character we'll redefine it as "a sequence of any characters except blanks, tabs, line feeds and carriage returns."

The algorithm used by K&P is, in my opinion, too complex. It uses a flag, inword, to keep track of whether the file pointer is "in a word", tests that flag, and then changes it, or not, depending on the results of that test.

Consider TAB, LF, CR and BLANK. Let’s call these delimiters. The signal to increment the count is a transition from a delimiter to a non-delimiter. Thus, we need to keep track of the previous character in the stream. The problem of "what was the previous character when we read the first character" is trivial. We need only assign it some value. That value must be a delimiter otherwise the first word in the file will not get counted.

Program WordCnt ;
{
      WordCnt -- count words in standard input
}
Uses
   Tools ;
CONST
   DELIMITERS  :  Set of Char = [TAB, LF, CR, BLANK] ;
Var
   Ch,
   Prev  :  Char ;
   Count :  LongInt ;
begin { WordCnt }
   Prev  := BLANK ;
   Count := 0 ;
   while NOT eof do begin
      Read (Ch) ;
      if (Prev in DELIMITERS) AND (NOT(Ch in DELIMITERS)) then
             Count := Count + 1 ;
      Prev  := Ch
   end ;
   WriteLn (Count:0)
end.  { WordCnt }

Another departure from K&P is the use of a set and a typed constant. Typed constants allow values to be assigned to structured constant types, a feature of Turbo Pascal that K&P did not have access to. The use of a set makes the program more changeable (maintainable) since the choice of delimiters can be changed by changing their definition in line 8. For example

CONST
   NUL = Chr(0) ;
   DELIMITERS  :  Set of Char = [NUL .. BLANK] ;

In this case I would add NUL to the unit Tools (and I will later). DELIMITERS could also be added to Tools but I did not since I do not anticipate using DELIMITERS again. I also anticipate that other programs that use the concept of delimiters would not need the same definition so I kept the definition local.