Queue, Stack Overflow error when grabbing data using Char*

Question

0.00/5 (No votes)

See more:

Scenario:

Have a queue of CString's with size 30000. I am grabbing the data one by one.

Code:

C++

USES_CONVERSION

while (!DataQueue->empty())
{
	CString sTimeStamp = DataQueue->front();
	char* pChar = T2A(sTimeStamp);
	//do something with pChar
	DataQueue->pop();
}

The application is crashing throwing up a stack overflow error. If i remove the piece of code "char* pChar = T2A(sTimeStamp);", there is no error thrown and everything works fine. I think that the Char* line is having a memory leak or the memory is not freed and there by causing the complete usage of heap memory before the queue iteration completes.

This is all what i have tried with in the while loop but nothing worked, the application still crashes:

C++

char* pChar = sTimeStamp.GetBuffer(0);

char* pChar = T2A(sTimeStamp.GetBuffer(0));

char* pChar
pChar = sTimeStamp.GetBuffer(sTimeStamp.GetLength());

char* pChar
strcpy(pChar, (LPCTSTR)sTimeStamp);

char*	pChar1 = new char[];
delete [] pChar;

How do i solve the stack overflow error?

Posted 19-Aug-13 10:56am

amarasat

Updated 19-Aug-13 16:34pm

H.Brydon

v2

Add a Solution

Comments

Sergey Alexandrovich Kryukov 19-Aug-13 17:25pm

Debugger. Usually it's fairly simple. Your code does not reveal the problem.
—SA

3 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Accepted Answer · 2013-08-19T11:26:00

The code sample you show does not reveal the problem. Usually, this problem is easy enough to solve.

Almost 100% of certainty that this is result of "infinite" recursion or mutual recursion:
http://en.wikipedia.org/wiki/Recursion[^],
http://en.wikipedia.org/wiki/Mutual_recursion[^].

Such problems can be resolved in a very systematic way using the debugger. First, you observe where the exception is thrown. Put a break point before it happens and use the debugger window "Call stack". You will see where the calls come from. Find out the reason for infinite recursion and devise a correct condition of exit from recursion. Usually, the bug can be found very quickly if you combine debugging with simple logic.

You make an initial guess on at least one method which is attempted to get called "infinite" number of times. Usually it does not take long to find such place. You put break point(s) on a very beginning of such method(s) and try to confirm it happens. When the execution is stopped on a breakpoint, you can go up the stack or down the stack. It's more effective to go down: you keep the breakpoint and debug just one this method stepwise, making big steps at first, until you catch the same method being called deeper in stack (remember your breakpoint is still there). When it happens, you start over and go in smaller step until you pinpoint where the recursion goes. This time try to figure out why the condition of the recursion end is never met. At the same time you move your breakpoint(s) closer to the source of recursive call, narrowing your net.

It may sound difficult, but with little practice always gives 100% results, unlike the cases with different bugs of some unknown nature. In case of stack overflow, you can be 100% sure that you can find the problem before you start looking.

—SA

nv3 · Accepted Answer · 2013-08-19T20:18:00

Solution 2

The documentation of T2A tells you that it allocates its space for storing the converted character string from the stack. Any yes, this space is not returned until you exit the function. If you call T2A in a loop it will grab more an more of the stack until you finally reach a stack overflow. And that is what typically happens.

Solution: Don't use T2A but a single local buffer that you allocate yourself and convert into that buffer. The same buffer can be used in each iteration of the loop.

Posted 19-Aug-13 20:18pm

nv3

Comments

CPallini 20-Aug-13 4:26am

5.

nv3 20-Aug-13 4:52am

Thanks!

amarasat 20-Aug-13 9:31am

Thanks for the help nv3, i had problems in understanding local buffer, but Jochen's answer solved it.

nv3 20-Aug-13 10:23am

You are welcome.

Jochen Arndt · Accepted Answer · 2013-08-19T21:44:00

Solution 3

Solution 2 from nv3 explains what is wrong.

When using the CString class anyway, you can use CStringA which supports conversion from Unicode to ANSI with the assignment operator:

C++

while (!DataQueue->empty())
{
    // This assumes that DataQueue is a CString list
    // Then GetString() must be used to have a LPCTSTR
    CStringA sTimeStamp = DataQueue->front().GetString();
    // Get a const ptr
    // Use GetBuffer() instead if the string should be modified
    const char* pChar = sTimeStamp.GetString();
    DataQueue->pop();
}

Posted 19-Aug-13 21:44pm

Jochen Arndt

Comments

amarasat 20-Aug-13 9:29am

Oh my God,

Thanks a lot for your solution. It has worked and solved my stupid stackoverflow problem that i have been sitting for almost a day. This is what i am trying to search online, some method to construct the Char* which does not cause StackOverFlow.

Jochen Arndt 20-Aug-13 10:53am

Glad to here that it is working now. I hope you understand the problem described by nv3. My solution is what he suggested: The CStringA variable is the local buffer for the converted string.

Queue, Stack Overflow error when grabbing data using Char*

3 solutions

Solution 1

Solution 2

Solution 3

Add your solution here

Preview 0

Existing Members

...or Join us