From: rhh@tachy.uah.ualberta.ca (Roy Hann)
Date: 6 Dec 1994 06:56:49 GMT

helmc@sotovento.NoSubdomain.NoDomain (Hellawell M C) writes:
: Help I am having problems reading integer and floating point numbers into an
: sqlvar structure when I print out the contents of what sqldata is pointing
: to I get either 0 or 0.0 Here is just a fraction of code that sets type
: information
:  
: case -IISQ_MNY_TYPE:
: case IISQ_MNY_TYPE:
:		sqlda->sqlvar[x].sqltype = IISQ_FLT_TYPE;
: 		sqlda->sqlvar[x].sqllen = sizeof(double);
: 		sqlda->sqlvar[x].sqldata = (char *)calloc(1, sizeof(double));
: 		sqlda->sqlvar[x].sqlind = (short *)calloc(1, sizeof(short)); 
: 		break;
: case -IISQ_INT_TYPE:
: case IISQ_INT_TYPE:
:		sqlda->sqlvar[x].sqltype = IISQ_INT_TYPE;
: 		sqlda->sqlvar[x].sqllen = sizeof(long);
: 		sqlda->sqlvar[x].sqldata = (char *)calloc(1, sizeof(long));
: 		sqlda->sqlvar[x].sqlind = (short *)0; 
: 		break;

A few potential gotchas spring to mind.  The first thing that I notice
you doing differently from what I do (which works), is that you are
using "calloc".  Just glancing at the documentation on an Ultrix box 
(which is where I happen to be reading this), it does not explicitly
note that the space is allocated starting on a word boundary.  If it
does not force alignment, that could be a problem with some machines.

Also, you are allocating space for each column individually.  I don't
have a manual handy to check if it's important, but I always figure out
how big an area I need and then allocate a single contiguous
chunk--that is probably more efficient anyway (if you care about
milliseconds).

Apart from that, the other two things that have got me in the past
were: forgetting to allocate space for a short for the null indicator
when the column is nullable, and not adding space to align character 
strings on 4-byte word boundaries.

--Roy Hann

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