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PQescapeBytea & PQunescapeBytea

From: "Frost, Mr(dot) Michael (contractor)" <frost(at)nrlmry(dot)navy(dot)mil>
To: <pgsql-interfaces(at)postgresql(dot)org>
Subject: PQescapeBytea & PQunescapeBytea
Date: 2005-05-03 20:51:53
Message-ID: 5188F15076BC7A4DBB705747602058C11AAB88@mailhost (view raw, whole thread or download thread mbox)
Lists: pgsql-interfaces
Hi.  I am running 7.4.6 of postgres.  I have some data that I desire to
store as bytea in postgres.  The data is an array of floats.  I cast the
array of floats to a unsigned char and call PQescapeBytea to prepare the
data for ingest.  I insert it into the database, and then extract it
back out.  I then call PQunescapeBytea and cast it back to float to
return it to it's original.

However, I am probably doing something incorrect, since the before /
after data is not the same.

So, I eliminate the ingest into the database, and basically just called
the PQescapeBytea & PQunescapeBytea and I get different results.

In my example, I fill an array of 10 floats with values from 0.0 to 9.0.
I then cast this to unsigned char.  I then call PQescapeBytea.

for ( i = 0; i < 10; i++ )
   prsData = ( float ) i;

pData = ( unsigned char * ) prsData;

pEscapedData = PQescapeBytea ( pData, 40, &newSize );

// newSize comes back to be 161.

Then I call PQunescapeBytea with pEscapedData.  This returns a newSize
that is different from the original.

pUnescapedData = PQunescapeBytea ( pEscapedData, &newSize );

//  newSize comes back to be 130, but I expected it to be 40.

Any insight as to what I am doing incorrectly.?

Michael Frost
Computer Sciences Corporation
Phone:  831-656-4723
Fax:  831-656-4769
Email:  frost(at)nrlmry(dot)navy(dot)mil


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