OpenEuphoria

Re: Reading strings

• Posted by Chris Bensler <bensler at nt.net> Jan 21, 2007
• 493 views

Bernie Ryan wrote:
> 
> Hayden McKay wrote:
> > 
> > }}}
<eucode>
> > -----------------------------------------------------------------
> >                         -- string(atom p)
> > global function         -- returns a euphoria represented string.
> > 
> >     string(atom p)
> >     sequence st	                    -- place holder for string
> > 
> >     st = ""                         -- just an empty string :)
> >     for k = 0 to 256 by 1 do
> >         if peek(p + k) = 0 then     -- scan for '0' terminator
> >             st = peek({p, k})
> >         exit end if
> >     end for
> > 
> >     return st
> > 
> > end function
> > 
> > -----------------------------------------------------------------
> > </eucode>
{{{

> > A function to read 'c' style strings from memory.
> > Does anybody know a faster way?
> 
> Hayden:

Is it necessary to limit the string length?


>      Try this I don't know how fast it is.
> 
> }}}
<eucode>
>  -----------------------------------------------------------------
>  global function getstring(atom p)
> 
>      sequence st
>  
>      st = {peek(p)}
> 
>      while st[$] do
>        st &= peek(p + length(st))
>      end while 
> 
>      return st
> 
>  end function
>  -----------------------------------------------------------------
> </eucode>
{{{

> Bernie

I haven't tried Hayden's function, but I have compared a function before that
was similar to the one Bernie posted (it concatenates), and the following is
faster:

------------------------------------------------
global function peek_string(pointer addr)
------------------------------------------------
-- syntax: s = peek_string( x )
-- description:
--    retrieves a null-terminated string from a memory address.
 atom offset
  offset = addr
  while peek(offset) do offset +=1 end while
  return peek({addr,offset-addr})
end function

Pete: peek() will accept peek({lp,0}) which will result in a null string

Chris Bensler
~ The difference between ordinary and extraordinary is that little extra ~
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