dynamic-memory-allocation

Just out of curiosity, is the following legal? X* p = static_cast<X*>(operator new[](3 * sizeof(X))); new(p + 0) X(); new(p + 1) X(); new(p + 2) X(); delete[] p; // Am I allowed to use delete[] here? Or is it undefined behavior? Similarly: X* q = new X[3](); (q + 2)->~X(); (q + 1)->~X(); (q + 0)->~X(); operator delete[](q); I'm pretty sure both give UB. §5.3.4/12 says the array form of a new expression may add some arbitrary amount of overhead to the amount of memory allocated. The array delete can/could then do something with the extra memory it expects to be there, but isn't since you didn't

I recently posted a question about this, but this is a different question. I created a 2D arrays using dynamic memory allocation, after the matrix is used, we need to free the memory by delete it and I dont understand why we cant just use delete [] matrix to delete it instead of the method in the codes below int **matrix; // dynamically allocate an array matrix = new int *[row]; for (int count = 0; count < row; count++) matrix[count] = new int[col]; // free dynamically allocated memory for( int i = 0 ; i < *row ; i++ ) { delete [] matrix[i] ; delete [] matrix ; } Because the problem is because

i am trying to dynamically allocate memory into the heap and then assign values in those memory addresses. I understand how to allocate the memory but how would i assign for example the value in a register to that first dynamic memory address? This is what i have so far:` push rbp mov rbp, rsp ;initialize an empy stack to create activation records for the rest of the subroutines mov rax, 0x2d ;linux system call for brk() mov rbx, 0x0 ;to get the adress of the first adress we are allocating we must have 0 in rbx int 0x80 ;calls the linux operating system kernel for assistance mov [brk

Possible Duplicate: When you exit a C application, is the malloc-ed memory automatically freed? This question came to my mind when i was reading about how compulsory it is to use delete/free respectively when it comes to dynamic memory allocation in C/C++. I thought if the memory allocation persisted beyond the termination of my program execution, then yes it is compulsory; otherwise, why do i have to worry about freeing up the allocated space? Isn't the OS going to free it up automatically with process termination? How right am i? My question is that can int *ip = new int(8); persist beyond

I want to implement my own dynamic memory management system in order to add new features that help to manage memory in C++. I use Windows (XP) and Linux (Ubuntu). What is needed to implement functions like 'malloc' and 'free'? I think that I have to use lowest level system calls. For Windows, I have found the functions: GetProcessHeap, HeapAlloc, HeapCreate, HeapDestroy and HeapFree. For Linux, I have not found any system calls for heap management. On Linux, malloc and free are system calls, are not they? Thanks Edit: C++ does not provide garbage collector and garbage collector is slow. Some

#include<stdio.h> #include<string.h> char *y; y=(char *)malloc(40); // gives an error here int main() { strcpy(y,"hello world"); } error: conflicting types for 'y' error: previous declaration of 'y' was here warning: initialization makes integer from pointer without a cast error: initializer element is not constant warning: data definition has no type or storage class warning: passing arg 1 of `strcpy' makes pointer from integer without cast Now the real question is, can't we make the dynamic memory allocation globally? Why does it show an error when I use malloc globally? And the code works

we want to use pimpl idiom for certain parts of our project. These parts of the project also happen to be parts where dynamic memory allocation is forbidden and this decision is not in our control. So what i am asking is, is there a clean and nice way of implementing pimpl idiom without dynamic memory allocation? Edit Here are some other limitations: Embedded platform, Standard C++98, no external libraries, no templates. Warning: the code here only showcases the storage aspect, it is a skeleton, no dynamic aspect (construction, copy, move, destruction) has been taken into account. I would

This question already has an answer here: C Programming: malloc() inside another function 8 answers My apologies, I know many related questions have already been asked, so I will keep it very simple. Despite some years of programming I cannot find the correct syntax for resizing and modifying an array (or several) inside a function. For example, say I want a function to fill an array with a set of "n" numbers, where "n" is defined within the array: int main(int argc, char *argv[]) { float *data = NULL int n = myfunction(data); for(i=0;i<n;i++) printf("%f\n",data[i]); free(data); } int