IJ Language: replace backslashes


In Windows file path should contain double backslash instead of a single one, for example: “C:\Target” instead of “C:\Target”.
I define a string variable with path to the target file:

SourceImageFilePath = "C:\Target\Image.tif"

and want to replace all backslashes to double backslashes:

replace(SourceImageFilePath, "\\", "\\\\");

However, this command gives the error:

Error: java.util.regex.PatternSyntaxException: Unexpected internal error near index 1

^ in line 60:

  replace ( SourceImageFilePath , "\" , "\\" <)> ; 

What is the reason for this error and how do I fix this?

Thank you.

There is a much easier way:

Use forward slashes as path delimiters on Windows.

SourceImageFilePath = "C:/Target/Image.tif"
1 Like

Got it.
However, what is the issue with replace command?

Dear @AKazak
The back slash is probably being interpreted as an escape character. Here are some posts discussing it.
Also, if you want your macro to run on any computer, you can use File.seperator instead of using the forward slash. An example would look like this:

SourceImageFilePath = "C:"+File.seperator+"Target"+File.Seperator+"Image.tif"

Or you could use,

SourceImageFilePath = File.openDialog("Get File");

if you want to have the user specify a file.

Thank you.
The idea of using File.seperator is a good one.

However, currently, I think about creating a function that converts a regular Windows path, which one could copy from Windows explorer to that handled by ImageJ.

As for backslash: yes it seems that if one defines a string, then ImageJ treats backslashes as escape characters:

SourceImageFilePath = "C:\Target\Image.tif"

results in SourceImageFilePath actually storing “C:TargetImage.tif”.

Therefore the next question is: how do I disable escape character handling during string variable assignment or make is literal?

1 Like

Dear @AKazak
I’m not sure if this answers your question, but after lookin at the Built-in Macro Functions page, it would appear that double backslashes counts as escape characters. I would also make sure your version of Imagej is up to date.
For example, the following:

Source = "C:\\\\Target\\\\Image.tif";


Source = "C:\\Target\\Image.tif";


returns C:\\Target\\Image.tif and C:\Target\Image.tif Respectively

However, I’m not quite sure why you want to add double backslashes to the string in the first place. I’m assuming your trying to open some .tif images on a windows computer.
You could try:

SourceImageFilePath = File.openDialog("Get File");

and that should open your file without needing to modify the file path.

File.openDialog works fine.
However, I copy a file path from a clipboard and want to paste it to a string variable.

It seems that backslash escape character works even during string variable assignment.
Therefore nothing can be done, except for manually replace \ with \\ in a text editor…
It happens even on this forum: I put double slash to get \ :laughing: