C :: Uninitialized Value Was Created By A Heap Allocation / Memcheck With Valgrind
Aug 2, 2014
I discovered valgrind and started using it for my c code. But I get following error message at almost every malloc position, :
==19505== 40 errors in context 10 of 12: ==19505== Use of uninitialised value of size 8 ==19505== at 0x10000416E: my_method (main.c:662) ==19505== by 0x10000159E: main (main.c:182) ==19505== Uninitialised value was created by a heap allocation ==19505== at 0x47F1: malloc (vg_replace_malloc.c:302) ==19505== by 0x100001C21: my_method (main.c:333) ==19505== by 0x10000159E: main (main.c:182)
and I really don't understand what it means. I already googled it but I didn't find out what is my mistake.SO here i just put one example:
Code:
int main(int argc, char** argv) {
//i declare my variables at this position
Uint *used, *forbidden_jumps, *forbidden_jumpsV,
*forbidden_jump;
/*now i want to allocate one of them, this is my line 333 from the error message*/
//a_num is set during the execution of the program,
ALLOC(used, Uint, a_num);
}
[code].....
Is there any support page for the output of valgrind? I found it on the homepage.
I have airport class which should navigate planes, in its list to runways, with method move, theres a method prepare which changes the direction of flight to all planes, always before move is called, move just increments decrement x and y of plane in its list. But after calling two times in row airport->move(), I get screwed and I really dont know wheres the problem. Have I badly initiazed something? Iterator gets invalidated.
Valgrind Stacktrace Conditional jump or move depends on uninitialised value(s) ==26207== at 0x409601: plane::move() (in /home/xnovak11/Downloads/airport/main) ==26207== by 0x401FBD: airport::move() (in /home/xnovak11/Downloads/airport/main) ==26207== by 0x405FE1: io::start(std::istream&, std:stream&, std:stream&) (in /home/xnovak11/Downloads/airport/main)
This is the method where it fails. When I call it once, no problem, after second call I get instead of normal number in cout<<after move<< s1 i get like 8795456 ....
m_vRenderObjects.push_back(new Objects(mOperatorMesh)); /// this is never called ~Objects(void) { OutputDebugStringA("Cleanup Objects "); if (StateMachine != NULL)
I have a large hash table, where each index has a container that has a doubly linked list. Things work up until releasing the memory. Each record is created with malloc, and each record->data is also created with malloc and the associated string is copied in using strcpy(). The table itself is released in another part of the program and doesn't produce and error.
/** * valgrind --track-origins=yes */ ==16898== Conditional jump or move depends on uninitialised value(s) ==16898== at 0x8049685: shFree (SpellHash.c:110) ==16898== by 0x8049352: unload (dictionary.c:115) ==16898== by 0x8048E64: main (speller.c:158) ==16898== Uninitialised value was created by a heap allocation
[Code] .....
How to interpret valgrind. Error resolved on a small problem. Now running into issues on large (>10000 words to check) problems. It appears the virtual machine just can't keep up for some reason. Running the code on my local computer produces no errors, memory usage is minuscule, and profile tools don't report any issues.
==39800== Invalid free() / delete / delete[] / realloc() ==39800== at 0x4D9D: free (vg_replace_malloc.c:477) ==39800== by 0x10000C471: Tokenizer::~Tokenizer() (in ./a.out) ==39800== by 0x10000C424: Tokenizer::~Tokenizer() (in ./a.out) ==39800== by 0x100001B8B: main (in ./a.out) ==39800== Address 0x10002a778 is 8 bytes inside a block of size 7,208 alloc'd
I have kept dummy as the data to be aligned.I will update hours, minutes, and seconds , but will not use dummy in any case. If I don't initialize 'dummy' does it make any errors ? Do I need to initialize hours, minutes, seconds as well before I use the structure ? If so is there any particular reason ?
#include <iostream> #include <string> struct WeatherStats { double total_rainfall; int high_temp; int low_temp; int avg_temp;
[Code] ....
When I run this program I am able to input data for the three months but after inputting everything I am prompted with a run time error that states: Run time check failure#3: The variable 'temp' is being used without being initialized. I've underlined the statement that the compiler says is causing this error, yet there is no variable 'temp' in that statement.
Computer are very specific right? So in the problem statement total_yearly_temp = total_yearly_temp + temp.avg_temp; there is a variable called total_yearly_temp and one called temp.avg_temp, but there are none called temp. It can't be complaining about the WeatherStats variable I defined in the first line of the function called temp because I did the exact same thing in the previous function and there are no errors concerning that.
I keep getting the "Uninitialized Local Variable" error. But for my code it's says it's the variable 'pay' in my Manager Function. This is the only error that is popping up.
I've tried setting pay to 0 but when I do, I get a bunch of external errors. I've also tried assigning pay to WeeklySalary like this:
double pay = WeeklySalary;
//Calculating pay for a company
#include <iostream> #include <iomanip> using namespace std;
I am getting this message from Valgrind, As far as I can see what it points to is initialized. The memory it is referring to is freed in unload and I was not getting this error until after I added the check function. Valgrind was happy. Here is the code and the error message from Valgrind. I am trying to create a spell checker for an assignment for a online class I am taking. I just want to get this table working correctly before I add it to the rest of the program. The code seems to run fine but I have come to see that dos not mean much in C.
arortell@gentoo ~/Development/Projects/C_Projects/Data_Structures/HashTable $ valgrind --leak-check=full --track-origins=yes ./hashTable ==11360== Memcheck, a memory error detector ==11360== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. ==11360== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info ==11360== Command: ./hashTable
Code: fn(){ char c; if (runFirstTime){ #ifdef VC c=''; #else c='/'; #endif } ... // c is used in the rest of the function to construct some pathnames }
The problem is that the value of c is not defined the 2nd time the function is called (and subsequently). It somehow worked fine under CygWin compiled with gcc. So I didn't spot the flaw until it ran incorrectly under Windows complied with VC++ 2010. Then I found the error and changed the code to something like
So now it works correctly under Windows. Then I re-compiled the new code with gcc and to my surprise gcc produced exactly the same binary! How can this be? Does the gcc compiler see my flaw and fix it for me somehow?
So I'm going through and trying to do a recursive implementation of a Heap. I keep getting access violations for some reason on my sifts (_siftUp) - even though I'm trying to insert into sub[0] (currSize = 0 in the constructor). I don't think either of my sifts are implemented correctly, are they?
If I have an array, and want to make a heap tree out of it using make heap and sort heap, how would I do it? I'm struggling because I didn't take any course in data structure.
I tried googling stuff and I got to the following:
I know that memory addresses in the stack can contain either values or references to other memory addresses, but do these memory addresses also contain methods or are the methods themselves located in the heap?
The confusion comes from the fact that in C# a delegate variable can be assigned either a method's identifier, an inline function, a lambda expression, or a new instance of the delegate type with the method's identifier passed as an argument to the constructor. My guess is that assigning the method's identifier directly to the delegate variable is just a simplified way of calling the delegate type's constructor with the method's identifier as an argument to the parameter, something that the compiler handles for you.
But even in this last case, the delegate variable is said to point toward the method itself. In that case, does it mean that methods are stored in the heap, just as reference type values are?
I am creating a class that has a private array on the heap with a constructor that takes the size of the array and initializes it on the heap. Later I have to make a deconstructor delete the space and print out free after.In my code, I was able to heap a private array and make a deconstructor, but I don't know how to take the size of the array and initialize it on the heap. My guess is this:
int* size = new int();
Also when you initialize size on the heap, don't you also have to delete it too? If so, where, in the code, do you do that? Here is my code so far.
Class Student { private: int size; int* array = new int[size]; public: Student(); // Constructor ~Student(); // Deconstructor
[code]....
How do you make a constructor that takes the size of the array and initializes it on the heap
i want to write a c++ program to build min heap which gets above values from user. remember this program should not alloduplicate values to enter. it should discard duplicate values.
I recently posted a question related to creating a heap template class. The ultimate goal is to create a series of classes that serve a purpose that was overlooked in the Qt library that I need for my current project.
The current "end goal" is a PriorityQueue template that uses a comparer class which is inherited from a "template interface". Basically a pure virtual class template. Perhaps that is the mistake to begin with but hopefully not. (Is this a valid approach?)The problem I am getting is that when I compile the code, it says my derived comparer class is abstract.
I will include all related classes here. I doubt it is relevant but the templates and the classes based off them are in different namespaces.Here is the comparer "template interface":
// in global namespace template<class T> class IIMQOBJECTS_EXPORT IQComparer { virtual int compare(T& a, T& b) = 0; virtual bool equals(T& a, T& b) = 0; virtual bool isGreaterThan(T& a, T& b) = 0; virtual bool isLessThan(T& a, T& b) = 0; };
Here is the class that is supposed to be non-abstract but isn't recognized as such:
// in the application namespace AND IN SAME project that has the NetEventInfo class // all functions ARE defined/implemented in a cpp file class APPCORE_EXPORT NetEventInfoComparer : ::IQComparer<NetEventInfo*> { public: NetEventInfoComparer(); ~NetEventInfoComparer();
I used a heap viewer to check for memory leaks. I have many of them and its hard to find out where it is not being freed. Is their a way to use the debugger to log the addresses of the data it allocated on the heap. This way I can trace it back. Or is their any other way to fix memory leaks properly.
I've got a VERY experimental function which takes data stored to a file and assigns it to a multidimensional array on the heap. It's designed for infinite dimensions by recalling itself with updated information but I don't think this is very safe.
The template function creates a heap array using a TYPE**, and recalls itself to create the new dimensions. I want to replace this with the much safer method of assigning just a single heap memory array and then only assign using the recalling method (unless I can find anything else).
To do this though I need to know how single dimensional arrays are stored on the heap, as well as multi-dimensional (for n dimensions). Where I can find this information?
btw I only need this for the Windows operating system, 32bit, I'm not exactly sure what 'C++ style' this is but I'm using Microsoft's Visual Studio Express 2012 as my IDE, so whatever that uses.
This assignment is about Heap and PQ's to sort out jobs inside a printer. I'm far from finishing the assignment but the most important part isn't working. My issue is that nothing is getting stored inside the array. I keep getting crashes and at this point I'm not sure what to do. I notice that my destructor runs right after my "addJob" Function finishes, which is destroying the memory. Which might be why nothing gets stored inside OR I think my implementation of Heap/PQ is wrong.
Functions inside my test.cpp aren't properly done, they are made just to see if something is stored inside.
1. Check if I created the array correctly [PQtype.cpp / Heap.h/ PQType.h] 2. Am I even using/storing into the array. [Test.cpp "addJob" Function] 3. I'm also new to working with Class Templates.
I developed the following heap sort algorithm code, and for some reason anytime it goes above 4100 entries, the algorithm completely crashes. It works perfectly up until that point but I can't see why it would crash?
void heap_from_root(MVector &v, int i, int n) { int end=n,j=0; // Identify the lowest root and how many sons it has. If it only has one son, set j=1. if (n==1) { n = 0; j = 1; } else if ((n-2) % 2 == 0) { n = (n-2)/2; } else if ((n-1) % 2 == 0) { n = (n-1)/2; j=1; }
I recently upgraded my operating system from Windows XP to Windows 7 SP1 64 bit. We are using Visual Studio 2008 Professional Edition and Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production.
When I try to execute this code I am getting the below exceptions
HTML Code: try { CDatabase *pDatabase = CDatabaseConnection::getDatabaseConnectionProcessLog(); ORSProcessLog rsProcessLog(pDatabase);
[Code] .....
Where rsProcessLog is the CRecordset object using a successfully connected database pointer pDatabase
In 32- bit Debug version I get a message box at rsProcessLog.Close(); with the below text Debug Error
Program: ......Test.exe
HEAP CORRUPTION DETECTED: after Normal block (#506) at 0x0087F628. CRT detected that the application wrote to memory after end of heap buffer.
Memory allocated at f:ddvctoolsvc7libsshipatlmfcsrcmfcdbcore.cpp(2626)
(Please Retry to debug the application)
In 32- bit Release version I get a message box at rsProcessLog.Close(); with the below text Windows has triggered a breakpoint in Test.exe
This may be due to a corruption of the heap, which indicates a bug in Test.exe or any of the DLLS it has loaded.
This may also be due to the user pressing F12 while Test.exe has focus.
The output window may have more diagnostic information.
The above code was a working code in Windows XP with the rest of the env remaining the same and it continues to run in Windows XP but not in Windows 7.
I need to write a piece of code that opens a QuickTime VR image into an MFC Dialog. I drew a Dialog and put an "Apple QuickTime Control 2.0" into it. Then I created a Control variable in my Dialog class, called QtControl. In the OnInitDialog I set the file to open, calling the put_FileName of the control.
I tested it by:
- opening a dialog --> worked - closing it --> worked - opening again --> crashed. The error was:
"Windows has triggered a breakpoint in TestOcx.exe.
This may be due to a corruption of the heap, which indicates a bug in TestOcx.exe or any of the DLLs it has loaded.
This may also be due to the user pressing F12 while TestOcx.exe has focus.
The output window may have more diagnostic information."
I tried many things and googled a lot, but the only way that I found to avoid this crash was hardcoding a valid URL in the QtControl resources at compile time. In other words, if I write a valid absolute path to a .mov into the URL property of the QtControl from Visual Studio and compile it, then it works. Obviously, I can't do this because the absolute Path is valid only on my PC.
