Where is the difference between these two lines?

Check out the copy-pasta from my command window in matlab at the end.

I swapped between both lines via the arrow key. And reexecuting the same line gave the same result

I copied both lines into 2 different txt files to have notepad++ compare them, and the only difference it found was in the 'E'

So I tried both lines again, this time with a replaced E (made sure I didnt accidently add any accents or whatever).

I replaced the isfolder() with exist() and got the same weird results ( a 7 instead of logical 1).

But the result is still the same.

What is going on here?

K>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

K>> isfolder('E:\GIT\loop-test')

ans =

  logical

   1

K>> 
K>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

K>> 
K>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

K>> 
K>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

K>> 
K>> isfolder('E:\GIT\loop-test')

ans =

  logical

   1

K>> isfolder('E:\GIT\loop-test')

ans =

  logical

   1

K>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

>> isfolder('E:\GIT\loop-test')

ans =

  logical

   1

>> isfolder('E:\GIT\loop-test')

ans =

  logical

   1

>> isfolder('E:\GIT\loop-test')

ans =

  logical

   1

>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

>> isfolder('‪E:\GIT\loop-test')

ans =

  logical

   0

[Matt J]

I copied both lines into 2 different txt files to have notepad++ compare them, and the only difference it found was in the 'E'

In what way were the E's different?

[Guillaume]

Store the two different strings in two variables, e.g:

path1 = 'E:\...'
path2 = 'E:\...'  %your two different paths, any difference has been removed when you pasted them here

then show us the output of

double(path1)
double(path2)

[Matt J]

Check out the copy-pasta

Sounds delicious ;)

[mahoromax]

Sadly the addon for notepad++ only showed me where the text has differences, not what difference.

Okay, so this looks like quite a difference. O_o

>> double(path1)

ans =

  Columns 1 through 7

        8234          69          58          92          71          73          84

  Columns 8 through 14

          92         108         111         111         112          45         116

  Columns 15 through 17

         101         115         116

>> double path2

ans =

   112    97   116   104    50

   

[mahoromax]

I might also have found out, where I get those "corrupt" paths from:

I usually go to the "security" section of windows explorers properties window, to copy the object path from there.

[Guillaume]

An easier way to get the path of any object on Windows, is to press shift and right click on the object in explorer. In the extended context menu that pops up, select copy as path. This won't have any left-to-right or right-to-left control characters as well.

Answer 1

[mahoromax]

So to summarize:

culprit was an invisible character, that windows copied when I took the filepath from the explorer properties' window

Smoother way: Shift + Rightclick and use "copy as path"

Thanks a lot @guillaume, Matt J and Rik.

And sorry for answering in a chaotic way (I first commented on the answer and then on the comments )

Answer 2

[Matt J]

My guess is that you have called the isfolder command with two different versions of the input, but with hidden characters or accents that make them look the same. Because the differences are not visible, you are unable to know which version you are executing when you use the arrow keys to scroll through the command history.

[Guillaume]

Answering the question in my comment would make it immediately clear if there are different characters in each string.

[mahoromax]

I can "remember" how many calls in the past which call was, and hence differentiate both

What I dont understand is why those hidden characters would not be registered in a comparison of both commands in a txt file?

I found out that if I replace the " 'E " instead of only " ' " or "E" the code works.

What kind of invisible character could that be?

[Rik]

The different character are still in the post (? for forum Unicode support). I copied the text from the post for both the true and false output.

T='E:\GIT\loop-test';
F='‪E:\GIT\loop-test';
double(T(1:3))
double(F(1:3))

The false version starts with char(8234).

Valid paths in Windows don't have a lot of limitations (link), but you're probably limited to 32-255 (excluding special characters). "The current code page" is likely something like cp1252, but apparently could support more chars. If you're certain about the code page in use on your system, you could filter all other chars away before calling isfolder.

[Guillaume]

So F starts with unicode 202A, which is an invisible control character and indeed may be taken into account by the OS (nothing to do with matlab here, it's the OS that parses the path ultimately).

We can't explain why that character got there, maybe see this, but whenever you see this sort of behaviour suspect invisible characters or characters that look the same but are actually different.

Hence why I asked initially the conversion to double.