I am working on a c++ module, where large amount of data needs to be
written to a stream and str() method is been used to assign the value
of this to the char*. This produces the intended result. But when i run
purify on it i get the following results.

[W] MLK: Memory leak of 8656 bytes from 9 blocks allocated in
strstreambuf::doallocate(void) [Builder.exe]
Distribution of leaked blocks
987 bytes from 1 block of 987 bytes (0x03977ea8)
980 bytes from 1 block of 980 bytes (0x038ff010)
976 bytes from 1 block of 976 bytes (0x03974cf8)
969 bytes from 1 block of 969 bytes (0x03969290)
962 bytes from 1 block of 962 bytes (0x03967a00)
960 bytes from 1 block of 960 bytes (0x03965d78)
958 bytes from 1 block of 958 bytes (0x038fe388)
957 bytes from 1 block of 957 bytes (0x003961f8)
907 bytes from 1 block of 907 bytes (0x041080b0)
Allocation location
new(UINT,int,char const*,int) [dbgnew.cpp:46]
strstreambuf::doallocate(void) [_strstre.cpp:201]
strstreambuf::overflow(int) [_strstre.cpp:256]
streambuf::xsputn(char const*,int) [streamb.cpp:182]
streambuf::sputn(char const*,int) [.\.\streamb.h:187]
ostream::writepad(char const*,char const*)
[ostream.cpp:166]
ostream::<<(char const*) [ostream.cpp:61]
writeInvisibleObject(char *,char *,char *,char const*)
[E:\Builder\src\main.cpp:2499]

This happens at the line where the char* is been assigned to the
strstream variable.

strstream strmvar;
strmvar << dataChar;

char* datadetail = strmvar.str();
delete datadetail;

Initially i assumed the reason to be writing a char* to the strstream
variable. But the error occured when i tried with int even. The purify
results indicate that it if beacuse of a overflow to the strstream var.
As for as my understanding the new memory that is been allocated was
never deleted. Since the program involves a huge amount of data this
could occur. Is the overflow the cause for the leak? Is there a way to
get rid of this leak? I definitely need to remove this as we are
running the code in batch mode for a set of input files. and this may
affect the performance of the application when run continously and may
lead to out of memory error even.

Can someone help me?

nithya4u@gmail.com wrote:

I am working on a c++ module, where large amount of data needs to be
written to a stream and str() method is been used to assign the value
of this to the char*. This produces the intended result. But when i run
purify on it i get the following results.
>
[W] MLK: Memory leak of 8656 bytes from 9 blocks allocated in
strstreambuf::doallocate(void) [Builder.exe]
Distribution of leaked blocks
987 bytes from 1 block of 987 bytes (0x03977ea8)
980 bytes from 1 block of 980 bytes (0x038ff010)
976 bytes from 1 block of 976 bytes (0x03974cf8)
969 bytes from 1 block of 969 bytes (0x03969290)
962 bytes from 1 block of 962 bytes (0x03967a00)
960 bytes from 1 block of 960 bytes (0x03965d78)
958 bytes from 1 block of 958 bytes (0x038fe388)
957 bytes from 1 block of 957 bytes (0x003961f8)
907 bytes from 1 block of 907 bytes (0x041080b0)
Allocation location
new(UINT,int,char const*,int) [dbgnew.cpp:46]
strstreambuf::doallocate(void) [_strstre.cpp:201]
strstreambuf::overflow(int) [_strstre.cpp:256]
streambuf::xsputn(char const*,int) [streamb.cpp:182]
streambuf::sputn(char const*,int) [.\.\streamb.h:187]
ostream::writepad(char const*,char const*)
[ostream.cpp:166]
ostream::<<(char const*) [ostream.cpp:61]
writeInvisibleObject(char *,char *,char *,char const*)
[E:\Builder\src\main.cpp:2499]
>
This happens at the line where the char* is been assigned to the
strstream variable.
>
strstream strmvar;
strmvar << dataChar;
>
char* datadetail = strmvar.str();
delete datadetail;
>
Initially i assumed the reason to be writing a char* to the strstream
variable. But the error occured when i tried with int even. The purify
results indicate that it if beacuse of a overflow to the strstream var.
As for as my understanding the new memory that is been allocated was
never deleted. Since the program involves a huge amount of data this
could occur. Is the overflow the cause for the leak? Is there a way to
get rid of this leak? I definitely need to remove this as we are
running the code in batch mode for a set of input files. and this may
affect the performance of the application when run continously and may
lead to out of memory error even.
>
Can someone help me?

First, you should use std::stringstreams instead of std::strstreams if
at all possible. The latter have been deprecated.

Second, I think your problem might be that you forgot to terminate the
strstream with std::ends:

strstream strmvar;
strmvar << dataChar << ends;

Cheers! --M

nithya4u@gmail.com wrote:

>
strstream strmvar;
strmvar << dataChar;
>
char* datadetail = strmvar.str();
delete datadetail;

delete [] datadetail;

I'm surprised Putrify doesn't give you an explicit error on this
one.

Ron Natalie wrote:

nithya4u@gmail.com wrote:
>

>
delete [] datadetail;
>
I'm surprised Putrify doesn't give you an explicit error on this
one.

Thanks. Since i am working on Windows probably purify didn't throw an
error on this.

I solved the problem that i had stated. That was because of the failure
to use freeze method. Once i unfreezed the buffer the destructor itself
took care of the deallocation of the strstream variable.

strmvar.rdbuf()->freeze(0);

made me fix the problem. Is this going to be a problem when I port the
application to UNIX? Do I need to make any changes to make it work?

mlimber wrote:

nithya4u@gmail.com wrote:

>
First, you should use std::stringstreams instead of std::strstreams if
at all possible. The latter have been deprecated.
>
Second, I think your problem might be that you forgot to terminate the
strstream with std::ends:
>
strstream strmvar;
strmvar << dataChar << ends;
>
Cheers! --M

Once you are done with object of strstream that's strmvar call
freeze(true) on strmvar.
strmvar.freeze(true);
I too had the same problem earlier.
This worked fine.
But change the deprecated strstream to stringstream.

Regards
Sunil

nithya4u@gmail.com wrote:

Ron Natalie wrote:

>
Thanks. Since i am working on Windows probably purify didn't throw an
error on this.
>
I solved the problem that i had stated. That was because of the failure
to use freeze method. Once i unfreezed the buffer the destructor itself
took care of the deallocation of the strstream variable.
>
strmvar.rdbuf()->freeze(0);
>
made me fix the problem. Is this going to be a problem when I port the
application to UNIX? Do I need to make any changes to make it work?

As long as you are able to change things, switch to std::stringstreams
without delay, and your problems will all magically go away! (Ok,
that's an exaggeration, but it will likely help since memory management
will be much simpler.)

Cheers! --M