OpenEuphoria

1. Does 'seek' have to used with 'if'.....

• Posted by John F Dutcher <John_Dutcher at urmc.rochester.edu> Oct 15, 2004
• 665 views

Here's a brief code sample that fails on the first occurence of the 'seek'
attempt with this message:

Syntax error:
... "expected possibly to see 'end', not a function"
      'seek(fn, tobyte)'

include machine.e
   include file.e
   include get.e
   without warning
   without type_check	
   crash_file("error-messages.txt")
   integer fn 	
   integer tobyte
   sequence resdata 	
   fn=open("dsysmst.dat","rb")
   if fn < 1 then
  	puts(1, "Unable to open the disk file\n")
        abort(fn)
   else 
     tobyte = 0
     seek (fn, tobyte)
     for i = 1 to 10 do 
        resdata = get_bytes(fn, 40)
        puts(1, resdata & '\n')
        tobyte = tobyte + 2690
        seek (fn, tobyte)
     end for   
   end if  
   close(fn)
   puts(1,"Test display of records completed") 

3. Re: Does 'seek' have to used with 'if'.....

• Posted by cklester <cklester at yahoo.com> Oct 15, 2004
• 641 views

John F Dutcher wrote:
> 
>    else 
>      tobyte = 0
>      seek (fn, tobyte)

seek() is a function, and therefore needs to be assigned to something.

For example:

   junk = seek(fn,tobyte) 


-=ck
"Programming in a state of EUPHORIA."
http://www.cklester.com/euphoria/

5. Re: Does 'seek' have to used with 'if'.....

• Posted by "Kat" <gertie at visionsix.com> Oct 15, 2004
• 665 views

On 15 Oct 2004, at 9:30, dirk dekker wrote:

>
>
> posted by: dirk dekker <dirk at induxion.nl>
>
> Hi,
> thanks for your answer,
> I do not understand the items. I just downloaded the samples and expected=
 to
> have a working program. But that's not true. I walked exactly the instruc=
tions
> but nevertheless : no success. Maybe you know what I am doing wrong with =
the
> isntallation of some examples.=20

This is where the confusion happens:
include file.e
i1 = seek(fn, i2)  <<== see it is assigned

Example:=20=20
 include file.e

integer fn
fn = open("mydata", "rb")
-- read and display first line of file 3 times:
for i = 1 to 3 do
    puts(1, gets(fn))

    if seek(fn, 0) then <<== no assign?

        puts(1, "rewind failed!\n")
    end if
end for

But there is an assignment made in the 2nd example, it is evaluated in the =
if
command. It's hidden. It's a concept of computer programming to pass the=

results of a function to another function without the programmer using it=

directly.

like:
trace(not(seek(fn, 0)))
puts(1,sprintf("%d",seek(fn, 0))&"\n")
set %swrk. [ $+ [ %net ] $+ . $+ [ %swrk.chan ] $+ ] .history $gettok(
%swrk. [ $+ [ %net ] $+ . $+ [ %swrk.chan ] $+ ] .history , 2- , $asc(=02) =
)


> So I noticed that to start a program I have to
> open a DOS-box. Am I right? Regards, Dirk

No. you do not haveto open any dosbox or window. But puts() to '1' is the=

dosbox, and will open a window. puts() to a file will not open a dosbox. Th=
e
windows and linux commands work differently. Look in the win32lib (or other=

windows libraries) examples for easy "real" windows writing. Geluk!

Kat

7. Re: Does 'seek' have to used with 'if'.....

• Posted by irv mullins <irvm at ellijay.com> Oct 15, 2004
• 625 views

dirk dekker wrote:
> 
> Hi ,
> when I start the example : web browser.exw; the result is an ex.err
> See this below:
> 
> d:\EUPHORIA\include\win32lib.ew:7224 in function validId() 
> ... called from d:\EUPHORIA\include\win32lib.ew:10956 in function getSize()  
> ... called from d:\EUPHORIA\include\win32lib.ew:11190 in function getExtent() 
>

I think you are using an old version of Win32Lib. The line numbers you 
refer to here are not in the functions named, at least not in the latest 
version (60.6) of Win32lib.

Irv

9. Re: Does 'seek' have to used with 'if'.....

• Posted by Derek Parnell <ddparnell at bigpond.com> Oct 15, 2004
• 624 views
• Last edited Oct 16, 2004

John F Dutcher wrote:
> 
> Here's a brief code sample that fails on the first occurence of the 'seek'
> attempt with this message:
> 
> Syntax error:
> ... "expected possibly to see 'end', not a function"
>       'seek(fn, tobyte)'

Hi John,
yes, you fell for the old 'using-a-function-as-a-procedure' trick. I fall
the same thing at least half a dozen times a day too! 

The rule in Euphoria is that a program *must* always do something with
the returned value from a function call. And 'seek' is a function. It 
always returns a value. Its your choice how you use it, but you must 
use it.

The value that 'seek' returns can be useful at times, but one easy way
to ignore it is to do this sort of thing ...

First, create a new *procedure*. Something like this will do ...

  procedure set_file_position(integer fn, atom where)
     fn = seek(fn,where)
  end procedure

Then instead of using 'seek', use 'set_file_position'!

Such as ...

   tobyte = 0
   set_file_position(fn, tobyte)


Hope this helps.
-- 
Derek Parnell
Melbourne, Australia