Math Forum Discussions

dpb

Posts: 6,677
Registered: 6/7/07

Re: textscan: handling spaces in fixed-width data
Posted: Jan 7, 2013 10:36 AM

Plain Text

On 1/7/2013 6:46 AM, David wrote:
> Hi dpb, Thanks for your messages! It really appears strange, that
> textscan handles the space different than other characters while scanning.
...

It's an unfortunate wart that comes from Matlab being written in C and
therefore using the *scanf() functions in the C i/o library and runtime.

I finally did find the normative text in the C Standard so it can't even
be blamed on a bad implementation; it's the result of a (misguided imo)
choice in the language definition to "eat" white space on the apparent
assumption that all input should be delimited--

From the C99 Standard (C99 7.19.6.2p8:)

> Input white-space characters (as specified by the isspace function)
> are skipped, unless the specification includes a [, c, or n
> specifier.241)

I've commented for years about not having an alternate Fortran-like
FORMAT specification that would solve many of the problems w/ the C
format strings (like also not being able to have repeat specifiers but
having to resort to the butt-ugly repmat() nonsense) that would fix the
problem but the seeds have fallen upon barren ground it seems...

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