<div dir="ltr">Or, maybe, what he's after is<div><br></div><div style>(for-each display <span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:12.666666984558105px"> </span><span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:12.666666984558105px">'("" "0" "" "0")) ?</span></div> <div style><span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:12.666666984558105px"><br></span></div><div style><span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:12.666666984558105px">(just guessing)</span></div> <div style><span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:12.666666984558105px"><br></span></div><div style><span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:12.666666984558105px">Cheers</span></div> <div style><span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:12.666666984558105px">P.</span></div><div style><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Apr 20, 2013 at 2:56 AM, Danny Yoo <span dir="ltr"><<a href="mailto:dyoo@hashcollision.org" target="_blank">dyoo@hashcollision.org</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">On Fri, Apr 19, 2013 at 6:47 PM, Kejia柯嘉 <<a href="mailto:w.kejia@gmail.com">w.kejia@gmail.com</a>> wrote:<br> > Hi Yoo,<br> ><br> > You may try (display '("" "0" "" "0")), and you will find two whitepaces<br> > between 0.<br> <br> <br> </div>The function "display" delimits between elements of a list by<br> inserting a space between each pair. It simply turns out that<br> displaying the empty string doesn't do anything. The output you're<br> seeing should be consistent with that behavior.<br> <br> Given:<br> <br> '("" "0" "" "0")<br> <br> It is displaying:<br> <br> the left-paren,<br> the "",<br> the space delimiter,<br> the "0",<br> the space delimiter,<br> the "",<br> the space delimiter,<br> the "0",<br> the right-paren.<br> <br> <br> Why are you using display to look at the content of lists? Usually,<br> write or print is more appropriate:<br> <br> <a href="http://docs.racket-lang.org/guide/read-write.html" target="_blank">http://docs.racket-lang.org/guide/read-write.html</a><br> <div class="im HOEnZb"><br> <br> <br> <br> ><br> > 在 2013年4月19日星期五，Danny Yoo 写道：<br> ><br> >> On Fri, Apr 19, 2013 at 5:44 PM, Kejia柯嘉 <<a href="mailto:w.kejia@gmail.com">w.kejia@gmail.com</a>> wrote:<br> >> > Hi all,<br> >> ><br> >> > In DrRacket, why is there an extra empty string (`[]`between 0s) in<br> >> > the list:`'("" "0" "" "0")`. This generates `([]0[][]0)`, instead of<br> >> > `([]0[]0)`.<br> >><br> >><br> >> Unfortunately, the question here is ambiguous. What are you trying to<br> >> do? Can you show us the code you are using to distinguish the empty<br> >> string? What expression are you trying to evaluate such that you get<br> >> this list in the first place?<br> ><br> ><br> ><br> > --<br> ><br> > ☵☯☲<br> ><br> ><br> <br> </div><div class="HOEnZb"><div class="h5">____________________<br> Racket Users list:<br> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a><br> </div></div></blockquote></div><br></div></div>