[Octave-bug-tracker] [bug #44745] single quoted string in sprintf is interpreted

[ederag]

URL:
  <http://savannah.gnu.org/bugs/?44745>

                 Summary: single quoted string in sprintf is interpreted
                 Project: GNU Octave
            Submitted by: ederag
            Submitted on: Mon 06 Apr 2015 05:37:53 PM GMT
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Documentation
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.0.0-rc2
        Operating System: GNU/Linux

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Details:


sprintf('\lambda = %.1f', 532)


yields

warning: unrecognized escape sequence '\l' -- converting to 'l'


This is unexpected, since the documentation for strings
<https://www.gnu.org/software/octave/doc/interpreter/Escape-Sequences-in-String-Constants.html#Escape-Sequences-in-String-Constants>
states that 
"In single-quoted strings, backslash is not a special character"

And the sprintf documentation
<https://www.gnu.org/software/octave/doc/interpreter/Formatted-Output.html#Formatted-Output>
does not appear to mention anything about that:
"This is like printf, except that the output is returned as a string. Unlike
the C library function, which requires you to provide a suitably sized string
as an argument, Octave’s sprintf function returns the string, automatically
sized to hold all of the items converted."

Is it a bug, or is it done on purpose ?
I infer the latter, from a comment from Soren
<http://octave.1599824.n4.nabble.com/Re-Single-vs-Double-Quotes-td3907882.html>:
"deviate from this rule just as the '*printf' functions do."

Then, after 

"The following functions are available for formatted output. They are modeled
after the C language functions of the same name, but they interpret the format
template differently in order to improve the performance of printing vector
and matrix values."

something like

"Beware that these functions will interpret the backslashes in the template
string, even if this is a single quote string"

could be helpful ?


Note this happens also under 3.8.2.




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