Validating Data in C programming

[gurdz]

Does anyone know how to perform data validation in C? I have searched
google for every possible result, and I either end up with data
validation for C++ or nothing at all. I have also searched websites
such as planet-source-code.com, but my search has been in vain.

Can someone please help me out. Or at least, point me in the right
direction?

Thank you very much. :)

[MQ]

gurdz wrote:

Does anyone know how to perform data validation in C? I have searched
google for every possible result, and I either end up with data
validation for C++ or nothing at all. I have also searched websites
such as planet-source-code.com, but my search has been in vain.

Can someone please help me out. Or at least, point me in the right
direction?

Thank you very much. :)

Data validation is a generic programming technique that is language
independant. It is just the process of checking that data input to
your program is within the range of expected values, etc. If you are
expecting a number between 1 and 10, check that it is a number between
1 and 10 before using it. What is so hard about that? Unless I am not
understanding your question...

[Flash Gordon]

gurdz wrote:

Does anyone know how to perform data validation in C?

Yes, you look at the data and see if it matches your validation rules.

I have searched
google for every possible result, and I either end up with data
validation for C++ or nothing at all. I have also searched websites
such as planet-source-code.com, but my search has been in vain.

Can someone please help me out. Or at least, point me in the right
direction?

It really depends on what the data you are trying to validate is, what
the rules are, and where the data is coming from. There is no one size
fits all solution.
--
Flash Gordon
Still sigless on this computer.

[Richard Heathfield]

Flash Gordon said:

<snip>

>
It really depends on what the data you are trying to validate is, what
the rules are, and where the data is coming from. There is no one size
fits all solution.

Yes, there is.

The following fragment is taken from the source code used by a major UK
bank, the identity of which will remain anonymous (to protect the guilty).
It was spotted during Y2K work in the late 1990s:

if(d != 6)
{
d = 6;
}

Viola! All numbers are 6, even if they aren't. QED.

How we laughed! We laughed and laughed and laughed, until we stopped.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at above domain (but drop the www, obviously)

[lovecreatesbeauty]

Richard Heathfield wrote:

The following fragment is taken from the source code used by a major UK
bank, the identity of which will remain anonymous (to protect the guilty).
It was spotted during Y2K work in the late 1990s:

if(d != 6)
{
d = 6;
}

Viola! All numbers are 6, even if they aren't. QED.

How we laughed! We laughed and laughed and laughed, until we stopped.

It is possible that there are occasions for using it.

[MQ]

Richard Heathfield wrote:

The following fragment is taken from the source code used by a major UK
bank, the identity of which will remain anonymous (to protect the guilty).
It was spotted during Y2K work in the late 1990s:

if(d != 6)
{
d = 6;
}

I don't think that it is any secret that banks have their own brand of
logic, that seems to err in their favour

[Andrew Poelstra]

On 2006-08-05, lovecreatesbeau ty <lo************ ***@gmail.comwr ote:

>
Richard Heathfield wrote:

>The following fragment is taken from the source code used by a major UK
bank, the identity of which will remain anonymous (to protect the guilty).
It was spotted during Y2K work in the late 1990s:

if(d != 6)
{
d = 6;
}

Viola! All numbers are 6, even if they aren't. QED.

How we laughed! We laughed and laughed and laughed, until we stopped.

It is possible that there are occasions for using it.

....where typing `d = 6' or even just `6' wouldn't suffice?

--
Andrew Poelstra <http://www.wpsoftware. net/projects>
To reach me by email, use `apoelstra' at the above domain.
"Do BOTH ends of the cable need to be plugged in?" -Anon.

[Malcolm]

"Andrew Poelstra" <ap*******@fals e.sitewrote

On 2006-08-05, lovecreatesbeau ty <lo************ ***@gmail.comwr ote:

>>
Richard Heathfield wrote:

>>The following fragment is taken from the source code used by a major UK
bank, the identity of which will remain anonymous (to protect the
guilty).
It was spotted during Y2K work in the late 1990s:

if(d != 6)
{
d = 6;
}

Viola! All numbers are 6, even if they aren't. QED.

How we laughed! We laughed and laughed and laughed, until we stopped.

It is possible that there are occasions for using it.

...where typing `d = 6' or even just `6' wouldn't suffice?

if(d != 6)
{
fprintf(stderr, "somethign fishy here\n");
d = 6;
}

if(d != 6)
{
// fprintf(stderr, "somethign fishy here\n");
d = 6;
}

Three months later, another compiler
Warning, non-standard comment line 3456

if((d != 6)
{
d = 6;
}

--
www.personal.leeds.ac.uk/~bgy1mm
freeware games to download.

[Al Balmer]

On Sat, 05 Aug 2006 10:18:58 +0000, Richard Heathfield
<in*****@invali d.invalidwrote:

>Flash Gordon said:

<snip>

>>
It really depends on what the data you are trying to validate is, what
the rules are, and where the data is coming from. There is no one size
fits all solution.

Yes, there is.

The following fragment is taken from the source code used by a major UK
bank, the identity of which will remain anonymous (to protect the guilty).
It was spotted during Y2K work in the late 1990s:

if(d != 6)
{
d = 6;
}

Viola! All numbers are 6, even if they aren't. QED.

How we laughed! We laughed and laughed and laughed, until we stopped.

<gLooks like a left-over debug statement. A place to set a
breakpoint.

--
Al Balmer
Sun City, AZ

[Eric Sosman]

Andrew Poelstra wrote:

On 2006-08-05, lovecreatesbeau ty <lo************ ***@gmail.comwr ote:

>>Richard Heathfield wrote:

>>>The following fragment is taken from the source code used by a major UK
bank, the identity of which will remain anonymous (to protect the guilty).
It was spotted during Y2K work in the late 1990s:

if(d != 6)
{
d = 6;
}

Viola! All numbers are 6, even if they aren't. QED.

How we laughed! We laughed and laughed and laughed, until we stopped.

It is possible that there are occasions for using it.

...where typing `d = 6' or even just `6' wouldn't suffice?

It's an optimization. On a virtual memory system, it avoids
setting the "dirty" bit for a memory page unnecessarily, thereby
avoiding the (potential) expense of a page-out operation later,
or at least not incurring the expense for no good purpose.

(Hmmm: That variable name, `d'. Was the author, by any
chance, named Reginald?)

--
Eric Sosman
es*****@acm-dot-org.invalid