removing a printf statement from my program causes it to crash!?

[Harman Dhaliwal]

Hi,
I am programming an in memory representation of a database and am at
the tail end, hopefully, of implementation. But the vexing point is
that my program runs fine with all my diagnostic printf statements, but
as soon as I remove the printf statements the program crashes with a
pointer error (usually tried reading x00000000 error).

I have tried everything from flushing the buffer, tracking done the
routine, etc... can anyone offer me some suggestions to something I
might try? Has anyone had a similiar error? What is going on with
printf that would cause the removal of it to prvent program execution?
Does printf empty a buffer that is overflowing? Please excuse my
lamentations but I've hit my head against this for almost 2 days.
Thank you in advance for any response.

[Snis Pilbor]

Hi Harman,

I'm not the world's best expert, but in my experience whenever you
have anomalies like this it suggests that dynamically allocated memory
is corrupt. Look closely to make sure everything that needs to be
allocated is allocated before use and that once anything is free'd, it
is never "used" again.

Harman Dhaliwal wrote:

Hi,
I am programming an in memory representation of a database and am at
the tail end, hopefully, of implementation. But the vexing point is
that my program runs fine with all my diagnostic printf statements, but
as soon as I remove the printf statements the program crashes with a
pointer error (usually tried reading x00000000 error).

I have tried everything from flushing the buffer, tracking done the
routine, etc... can anyone offer me some suggestions to something I
might try? Has anyone had a similiar error? What is going on with
printf that would cause the removal of it to prvent program execution?
Does printf empty a buffer that is overflowing? Please excuse my
lamentations but I've hit my head against this for almost 2 days.
Thank you in advance for any response.

[Joe Smith]

"Snis Pilbor" <sn********@yah oo.com> wrote in message

Hi Harman, I'm not the world's best expert, but in my experience whenever you
have anomalies like this it suggests that dynamically allocated memory
is corrupt. Look closely to make sure everything that needs to be
allocated is allocated before use and that once anything is free'd, it
is never "used" again.

Harman Dhaliwal wrote:

Hi,
I am programming an in memory representation of a database and am at
the tail end, hopefully, of implementation. But the vexing point is
that my program runs fine with all my diagnostic printf statements, but
as soon as I remove the printf statements the program crashes with a
pointer error (usually tried reading x00000000 error).

I have tried everything from flushing the buffer, tracking done the
routine, etc... can anyone offer me some suggestions to something I
might try? Has anyone had a similiar error? What is going on with
printf that would cause the removal of it to prvent program execution?
Does printf empty a buffer that is overflowing? Please excuse my
lamentations but I've hit my head against this for almost 2 days.
Thank you in advance for any response.

Mr. Pilbor, please don't top post. Have you (OP) been keeping an eye of the
return value on printf? joe

[Marc Thrun]

Harman Dhaliwal schrieb:

Hi,
I am programming an in memory representation of a database and am at
the tail end, hopefully, of implementation. But the vexing point is
that my program runs fine with all my diagnostic printf statements, but
as soon as I remove the printf statements the program crashes with a
pointer error (usually tried reading x00000000 error).

I have tried everything from flushing the buffer, tracking done the
routine, etc... can anyone offer me some suggestions to something I
might try? Has anyone had a similiar error? What is going on with
printf that would cause the removal of it to prvent program execution?
Does printf empty a buffer that is overflowing? Please excuse my
lamentations but I've hit my head against this for almost 2 days.
Thank you in advance for any response.

This is one downside of undefined behaviour - it might even seem to
work, until you remove this call to printf(). So your real mistake
happened somewhere before the printf() was called while your program was
executing.

--
Marc Thrun
http://www.tekwarrior.de/

[harmanpal]

I haven't been keeping track, but if a negative number is returned, how
can i use this to track my error? I am relatively new to C and am
approaching from a high level language (java) background

[Richard Heathfield]

ha*******@gmail .com said:

I am relatively new to C and am
approaching from a high level language (java) background

The cause of your C problem is an error in the way you are using pointers.

--
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)

[Joe Smith]

"Richard Heathfield"

ha*******@gmail .com said:

I am relatively new to C and am
approaching from a high level language (java) background

The cause of your C problem is an error in the way you are using pointers.

Did the claim that printf managed to print a negative number of characters
figure into this diagnosis? joe

[Keith Thompson]

"Joe Smith" <gr**********@n etzero.net> writes:

"Richard Heathfield"

ha*******@gmail .com said:

I am relatively new to C and am
approaching from a high level language (java) background

The cause of your C problem is an error in the way you are using pointers.

Did the claim that printf managed to print a negative number of characters
figure into this diagnosis? joe

I don't recall any such claim.

printf() returns the number of characters printed, or a negative value
if an error occurs. Even if it were possible for it to print a
negative number of characters, there would be no way for it to
indicate that it had done so.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Richard Heathfield]

Joe Smith said:

"Richard Heathfield"

ha*******@gmail .com said:

I am relatively new to C and am
approaching from a high level language (java) background

The cause of your C problem is an error in the way you are using
pointers.

Did the claim that printf managed to print a negative number of characters
figure into this diagnosis?

No, my diagnosis was based on the fact that the OP has a Java background.
--
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)

[Default User]

Harman Dhaliwal wrote:

Hi,
I am programming an in memory representation of a database and am at
the tail end, hopefully, of implementation. But the vexing point is
that my program runs fine with all my diagnostic printf statements,
but as soon as I remove the printf statements the program crashes
with a pointer error (usually tried reading x00000000 error).

I have tried everything from flushing the buffer, tracking done the
routine, etc... can anyone offer me some suggestions to something I
might try? Has anyone had a similiar error? What is going on with
printf that would cause the removal of it to prvent program execution?
Does printf empty a buffer that is overflowing? Please excuse my
lamentations but I've hit my head against this for almost 2 days.
Thank you in advance for any response.

How can we debug code you don't show? Seriously.

When something like that happens, you are probably overwriting some
automatic data or something like that.

Reduce it to a minimal, compilable program that demonstrates the
problem. Often you'll find it yourself when you do that. Otherwise,
post the code.


Brian