I must be missing something fundamental here. The following code fragment doesn’t work (VC++ 8.0 SP1) – the checked iterators in STL catch walking off the end of the source – transform_width is attempting to access the second element of the vector

 

typedef

    base64_from_binary<

        transform_width<vector<char>::const_iterator, 6, 8>

        > base64_t;

 

  vector<char> hippo(1);

  string enc(base64_t(hippo.begin()), base64_t(hippo.end())); // -> checked iterator assertion fires

 

In basic_text_oprimitive.ipp, the iterator is a pointer so it’s possible it may be silently doing something bad

  Andrew

 

From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Robert Ramey
Sent: Friday, January 04, 2008 11:58 AM
To: boost-users@lists.boost.org
Subject: [Spam:***** SpamScore] Re: [Boost-users] base 64 encoding

 

Take a look at basic_text_oprimitive.ipp around line # 64.

 

Note that I add "padding" here to address this problem.  Perhaps that is the missing

magic.  Hmmm. perhaps that code should be part of the iterator.

 

Also look at the code text_iterators_base64 in the serialization test suite.

 

Robert Ramey

 

"Eames, Andrew" <andrew@cognex.com> wrote in message news:8F37BF6F420455468C4BD57DD6BE199004C6146B@cobra.pc.cognex.com...

But there is still the problem with running off the end of the source – If the source is not a multiple of 3 bytes then the input iterator will run off the end of the input sequence which can cause an error.

  Andrew

 

From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Robert Ramey
Sent: Thursday, January 03, 2008 6:47 PM
To: boost-users@lists.boost.org
Subject: Re: [Boost-users] base 64 encoding

 

I had to separately record the number of bytes.  Then when I decode, just pull off that number of bytes.

 

Robert Ramey

 

"Eames, Andrew" <andrew@cognex.com> wrote in message news:8F37BF6F420455468C4BD57DD6BE199004C613F8@cobra.pc.cognex.com...

Hi,

I’m trying to encode base64 data by composing base64_from_binary with transform_width but this doesn’t appear to work correctly when the data is not a multiple of 3 long. What is the correct way to handle this  - do I have to handle the padding myself by extending the input data and then patching the tail of the result?

   Thanks

       Andrew

 


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