Questions tagged [memory-reallocation]
25 questions
6
votes
1 answer
Reallocate array with memcpy and memset
I've taken over some code, and came across a weird reallocation of an array. This is a function from within an Array class (used by the JsonValue)
void reserve( uint32_t newCapacity ) {
if ( newCapacity > length + additionalCapacity ) {
…
ChrisMM
- 8,448
- 13
- 29
- 48
6
votes
1 answer
What's the reallocation equivalent of std::aligned_alloc()?
I've noticed std::aligned_alloc() coming into C++17, and I like it. But - what happens when I need to reallocate? I can do this manually (assuming the available space at the currently-allocated address is just the amount of space I asked for), but…
einpoklum
- 118,144
- 57
- 340
- 684
2
votes
1 answer
Vulkan/VMA Change buffer size similar to `realloc`
Say I run into a situation where I would like to change a vulkan buffer's (VkBuffer) size. For example, if I wanted to add more vertices to an existing vertex buffer. How would I grow/shrink a VkBuffer? Would I be forced to just create a new buffer…
Rotartsi
- 527
- 5
- 19
2
votes
2 answers
Designing a resize function for a queue
I'm currently trying to design a public API for a queue data structure and resize function to change its size. My first intention was to do it in the following way:
typedef struct queue queue;
/**
* Resizes a given queue.
*
* Changes the size of…
St.Antario
- 26,175
- 41
- 130
- 318
2
votes
3 answers
Vulkan - 1 uniform buffer, N meshes - dynamic VkDeviceMemory
Suppose I'm rendering simple cubes at random positions.
Having 3 of them as the starting number of cubes, the application acquires a VkBuffer handle and binds it to a VkDeviceMemory in order to store the model matrices of all cubes consecutively in…
Carlos Romero
- 698
- 8
- 18
1
vote
2 answers
Explanation of "realloc doesn't require that ptr point to a memory but in practice does."
I am reading about the realloc function, i.e.
void *realloc(void *ptr, size_t size);
and the author of the textbook I'm reading (K.N. King "C Programming a Modern Approach", 2nd edition, p.421, last paragraph), at some point writes
Although…
utobi
- 279
- 8
- 16
1
vote
0 answers
Novice question about using realloc properly in practice
I'm trying to understand how to think about memory allocation from a practical perspective. I think I understand how to implement malloc and realloc in a basic sense, but I don't understand how to do it efficiently.
The examples I have in my books…
Gary
- 2,393
- 12
- 31
1
vote
1 answer
Segmentation Fault accessing array positions after realloc
Let's suppose I have this function:
void arrayExtendDouble(int **ptArr, int *size)
{
*ptArr = realloc(*ptArr, (*size * 2) * sizeof(int));
for(int i = (*size * 2) - 1; i >= *size; i--)
ptArr[i] = fib(i); //this will throw SEG…
walkman
- 478
- 1
- 8
- 21
1
vote
1 answer
How memory works if vectors inside class array are dynamically push_backed?
Assume that we have following class:
class Test {
public:
Test() {}
std::vector& getIntList() {
return intList;
}
private:
std::vector intList;
};
Also, we have following codes inside main function to declare class…
sungjun cho
- 809
- 7
- 18
1
vote
5 answers
Is there a way to change an array size using malloc and free functions only?
As homework, I have to write a function that changes an array's size using malloc and free functions only.
I know how to do it with realloc, but I don't know how to do it with malloc.
typedef struct{
int *tab;
int size;
}arr;
and I need to…
John
- 21
- 4
1
vote
1 answer
Problems using realloc for decreasing
I am trying to delete with realloc but it isn't working the way I expected...
void deallocates(int** v, int size, int original_size) {
int i;
*v = (int*)realloc(*v, sizeof(int) * size);
printf("\nAFTER REALLOC FOR SIZE = %d\n",…
Kevin Weitgenant
- 11
- 1
0
votes
0 answers
Issue with Queue Reallocation
#include
#include
int sizec,sizep;
struct queue
{
int *item;
int f,r,cnt;
};
typedef struct queue QUE;
void insertpriority(QUE *q)
{
if(q->cnt==sizep)
{
printf("Queue FULL\nReallocating\n");
q->item=((int…
0
votes
1 answer
Memory pool: force allocating resources (map / vector) to reallocate for continuity
I have a memory pool of fixed size. A custom allocator is used to put std::vector and std::unordered_map elements into that pool. Over time the memory pool gets fragmented and even though there might be enough memory available if you scrap all the…
glades
- 3,778
- 1
- 12
- 34
0
votes
1 answer
what's going wrong here with realloc()?
I am writing a code which uses realloc(). The following is a simplified version of the problem. Though the code looks obvious yet it doesn't seem to work.
// Program for implementing variable length integer…
Harsha
- 3
- 3
0
votes
2 answers
Why is realloc giving me inconsistent behaviour?
I am currently taking a procedural programming course at my school. We are using C with C99 standard. I discussed this with my instructor and I cannot understand why realloc() is working for his machine, but it is not working for mine.
The goal of…
Ryan Leung
- 11
- 3