Thank you for the quick response! I also think the correct result is '\0' with the size of 1x2.

Related Docs

https://docs.octave.org/v8.1.0/Common-String-Operations.html#index-undo_005fstring_005fescapes

: newstr = undo_string_escapes (string)
Convert special characters in strings back to their escaped forms.

Steps to Reproduce

Commands:

result = undo_string_escapes("\0")
whos result

The actual outputs:

result =
Variables visible from the current scope:

variables in scope: top scope

  Attr   Name        Size                     Bytes  Class
  ====   ====        ====                     =====  =====
         result      0x0                          0  char

Total is 0 elements using 0 bytes

My expected outputs:

result = \0
Variables visible from the current scope:

variables in scope: top scope

  Attr   Name        Size                     Bytes  Class
  ====   ====        ====                     =====  =====
         result      1x2                          2  char

Total is 2 elements using 2 bytes

Related Srcs

https://docs.octave.org/doxygen/dev/d7/da9/utils_8cc_source.html#l00986

 const char * undo_string_escape (char c)
 {
   if (! c)
     return "";

   switch (c)
     {
     case '\0':
       return R"(\0)";

     case '\a':
       return R"(\a)";

     case '\b': // backspace
       return R"(\b)";
   ...

I noticed that if c == '\0', the function will directly return "" instead of entering the first case of the switch block, thus undo_string_escapes("\0") will return an empty string.
I am wondering if this is a bug or an expected behavior? Thanks in advance for any responses!