[fpc-pascal]opening files from a text list

ZINTEL Gerhard gzintel at stadeln.faurecia.com
Fri Nov 28 13:03:41 CET 2003

Hello Donald,

>    If I have a file which contains on the first line...
> 49ers at Giants 16 13
>    I want to open a file called "49ers" and a file called 
> "Giants" and do
> some processing. Although FP handles strings, I believe that 
> you can still
> only read a character at a time, so I don't know how to read 
> "49ers" into
> a variable and open that file. The variable would be called 
> Away say, so
> how do I get "49ers" into Away so that I can then do
> assign(awayteam,Away)? I would then want to read "Giants" 
> into Home, and
> do assign(hometeam,Home), and go from there.

here is just another approach. The function NextToken scans a string for the
next token and gives it back. At the same time it shortens the original
sting. So with each call of it you'll get the next token available. It
handles blanks and tabs as white space character and is easily extendible
for other "white space" characters as ':', ';', ...

Here is the function with a short program for testing.

program TestNextToken;

var s : string;

  function nextToken(var s:string):string;
  { reads next token from string s and shortens s by this amount
  const whitespace = [' ',#9];	// whitespace should be blank and tab
  var l, start, stop : integer;
    l := length(s);
    start := 1;

    // searching first non whitespace character
    while (start <= l) and (s[start] in whitespace) do inc(start);

    // searching last non whitespace character
    while (stop <= l) and (not (s[stop] in whitespace)) do inc(stop);
    if s[stop] in whitespace then dec(stop);

    nextToken := copy(s,start,stop-start+1);

  s := '    aaa    bbb	ccc   ';	// a test string

In doing it this way is a bit more obvious, at least for me.

Gerhard Zintel
Faurecia Abgastechnik GmbH
Abt.: EGA
Fon.: +49 911 7610171
Fax.: +49 911 7610350
e-mail: GZintel<at>Stadeln.Faurecia.com

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