Debug Error Heap Corruption

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Windows Debug Heap Corruption

you, helping each other. Join them; it only takes a minute: Sign up Heap Corruption Detected: after Normal block (#126) up vote 1 down vote favorite I cannot for the life of me figure out why I am

Debugging Heap Corruption Windbg

getting this Debug Error: Heap Corruption Detected: after Normal block (#126) at 0x004cF6c0 CRT detected that the application wrote to memory after end of heap bugger. I understand that you need to free memory whenever you use new operator, which I did and I am still getting problems. for some reason the program doesn't end correctly in the recursive function. I debugged it and went through each line of code with breakpoints. At the end heap corruption detected of the if statement in countSum it somehow subtracts 1 from i and then reenters the if block.....which it is not supposed to do. Why is this occurring? /*this program calculates the sum of all the numbers in the array*/ #include #include using namespace std; /*prototype*/ void countSum(int, int, int, int*); int main(){ bool flag; int num; int sum = 0, j=0; int *array = new int; do{ system("cls"); cout<<"Enter a number into an array: "; cin>>array[j]; cout<<"add another?(y/n):"; char choice; cin>>choice; choice == 'y' ? flag = true : flag = false; j++; }while(flag); int size = j; countSum(sum, 0, size, array); //free memory delete array; array = 0; return 0; } void countSum(int sum, int i, int size, int *array){ if (i < size){ system("cls"); cout<<"The sum is :"<

is a basic string class to help in the understanding of dynamic memory allocation and pointer arithmetic with char arrays.

Heap Corruption Detected After Normal Block

The class was given to me in a very basic skeleton form heap corruption detected by dlmalloc with prototypes but no implementations, along with a test function to test my implementations. I CAN NOT heap corruption c++ use any C String functions in this assignment. The part of the program which is troubling is the append function, which just appends a parameter string215 object to http://stackoverflow.com/questions/11569473/heap-corruption-detected-after-normal-block-126 the end of the current string215 object. 1
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// Add a suffix to the end of this string. Allocates and frees memory. void string215::append(const string215 &suffix) { int dataLength = str_len(data); char *output = new char[dataLength+suffix.length()+1]; char *outTemp = output; char *dataTemp = data; for(int x = 0; x < dataLength; x++) { *output = *dataTemp; output++; dataTemp++; http://www.cplusplus.com/forum/general/94305/ } for(int y = 0; y < suffix.length(); y++) { *output = suffix.getchar(y); output++; } *output = '\0'; data = outTemp; } Execution of this function causes a heap corruption: Debug Error! Program: [Source path] HEAP CORRUPTION DETECTED: after Normal block (#136) at 0x005C4CC0. CRT detected that the application wrote to memory after end of heap buffer. Here is the description of the append function: Add the suffix to the end of this string. Allocates a new, larger, array; copies the old contents, followed by the suffix, to the new array; then frees the old array and updates the pointer to the new one. I've stepped through my append function using the debugger and still can't seem to figure out what's wrong with it. The error changes to a Debug Assertion Failed as soon as I try and free up the memory I allocated for output. Adding: delete[] output; after I assign outTemp to data generates: Debug Assertion Failed! Program: [Source path]\dbgdel.cpp Line: 52 Expression: _BLOCK_TYPE_IS_VALID(pHead->nBlockUse) ... Abort ||

, Windows Desktop Development > Visual C++ Question 0 Sign in to vote Hi, I wouldn't be asking this but this problem sometimes occurs directly after the line.. int main(int argc, char **argv[]) { PWCHARvar = (PWCHAR) https://social.msdn.microsoft.com/Forums/vstudio/en-US/2369982b-f74d-4061-b374-86ca8cb71418/buffer-overwrite-heap-corruption-detected?forum=vcgeneral malloc ((sizeof("some\\string") * sizeof(WCHAR)) + sizeof(WCHAR)); "HEAP CORRUPTION DETECTED after normal block (#60) at 0x00000000xxxxxxxx." "CRT detected the application wrote to memory after the end of the heap buffer." The problem never always occurs the same line and sometimes - usually - when I run through the code step by step (F10) lines are executed but the arrow jumps past lines unless I set a specific breakpoint on the line. Previously another error that heap corruption has occurred has been a write to invalid memory. (Error - 0x00000005, ACCESS_DENIED) The code seems fine when compiled as 32bit (no problems have ever occurred.) but the problems certainly occur when compiled as 64bit. I would like to know if it is possible that code that has been compiled has somehow been corrupted and is causing this error. I ask this only because I have had the HEAP CORRUPTION error occurred directly after debug heap corruption the first run statement. Thankyou, I really need the help. Wednesday, May 09, 2012 3:29 PM Reply | Quote Answers 1 Sign in to vote Heap corruptions are caused by writing too much to a memory buffer, and that is never a compiler error. Heap corruptions only manifest the next time you try to do something with the heap itself, like allocate more memory or free a block of memory, so it wouldn't occur after you overwrite the end of the buffer. As for the debugger jumping past lines, is your configuration set to release? When it optimises code, it may remove lines completely. The debugger will just not go onto those lines. If you want the best possible debug experience, make sure it is set to the debug configuration. For a simple way of causing a heap corruption, try the following code. It will always trigger on the free line. int wmain() { wchar_t *mystr = (wchar_t*)malloc(24); wcscpy(mystr, L"a longer string"); free(mystr); //will break here mystr = nullptr; return 0; } This causes a heap corruption because obviously the buffer can only store 12 characters (including the null terminator) and you copy more than that to the buffer. The obvious way to fix this is to increase the size of the buffer. If you want more help though, pro