Questions tagged [dynamic-memory-allocation]
Dynamic memory allocation, usually in the context of languages without garbage collection or mandatory or automatic reference counting, refers to the process or asking the operating system for a variable sized block of memory.
dynamic-memory-allocation
3,627
questions
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Segmentation fault on copy custom dynamic array [duplicate]
I'm trying to implement my custom dynamic array, like std::vector.
Dynamic array module code:
#ifndef ARRAY_H
#define ARRAY_H
#include <cstdlib>
#define CAPACITY_SCALE_FACTOR 2
template <...
0
votes
0
answers
36
views
How do I dynamically allocate memory for a multidimentional array in C? [duplicate]
Dynamically allocate memory for a multidimensional array (matrix) with a specified number of rows and columns.
How to allocate memory?
How to allocate memory for 2D array?
How to dynamically allocate ...
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0
answers
10
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How to Comparing Custom Malloc Package (CMU Malloc) with Standard Allocators Using Benchmarks
I am currently working on the CMU Malloc Lab and I have implemented my own malloc package in mm.c. I would like to benchmark my implementation not only with the Malloc Lab grading script but also ...
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votes
1
answer
26
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Why in Xcode debugger and instruments some memory is just "malloc(48 bytes)"
This, but meanwhile, other objects have fully qualified ObjectiveC class names, Swift class names, etc.
Why are some allocations written as "malloc(48 bytes)", while others aren't? Does this ...
- 2,661
0
votes
1
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82
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How can I prevent newly added users from having their age increased in the same iteration in a linked list in C?
I'm creating a Linked List of Users where one of the field is int age;
The user can choose from several options (addUser, findUser, exit, etc.)
on each iteration of the while loop I want to increase ...
- 156
0
votes
1
answer
30
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Does Spark 3.X on kubernetes supports dynamic allocation
We are using EKS master as spark master and as of now we are using fixed number of executors.
Now we want to enable dynamic allocation, does it supports in case of EKS.
I've seen some blogs saying to ...
0
votes
1
answer
80
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Why Can't I Successfully Allocate Space for a 1D Array Anywhere Besides Main? [duplicate]
I'm working with my professor's code that makes a list of 30 random numbers, and it started throwing errors when I tried to run it. I noticed that when I printed out the array contents within the ...
0
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1
answer
57
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Segfault with memcpy and array
I'm learning C and just ironing out my understanding of how memory is allocated. I'm playing around with the following code and it's segfaulting but I'm not sure why. Any pointers? (no pun intended)
#...
- 127
0
votes
2
answers
54
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Why can't I reassign flexible array member?
I have the following struct with a flexible array member. However, the code does not compile:
#define INITIAL_CAPACITY 5
typedef struct Object {
int size;
int elements[];
} Object;
int main(...
- 127
1
vote
1
answer
49
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Segmentation fault in using recursive selection sort in C language
I have i have wrote a C program. It should use recursive selection sort but segmentation fault occurs for big input (10000 or more). Debugger says that the segfault happens in findim function, but it'...
2
votes
1
answer
84
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Does redim use the heap or the stack memory in VBA?
I know this is quite strange to ask for a language that is far from a low-level language such as C and C++, but it caught my attention that for example if I do this:
Dim tempArray(0 To 2) As Integer
...
- 63
2
votes
2
answers
124
views
Unexpected result of string concatenation in C
The following C program should append an "/" after the path received in argv if the argument does not end in "/". The "odd for me" behavior is that after the first ...
- 43
0
votes
1
answer
64
views
How to default initialise non-POD object onto same address?
tl;dr; How can one make every instance of object have same constant address, and then assign it after user wants to change it?
I have a need to develop my own NULL (ish) objects, and would like to ...
- 1,021
7
votes
1
answer
138
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What will happen if I call `allocate_at_least(0)` according to C++23 standard?
As shown here, the behavior of allocate(0) is unspecified.
So, what will happen if I call allocate_at_least(0) according to C++23 standard? Is the behavior implementation-defined, or will it be ...
- 358
0
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0
answers
55
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Unexpected double free in single linked list
`I am trying to do a simple linked list. Everything works fine, but after the program calls ~List()
I am getting "double free in tcache2" and SIGABRT every time I run the program and ...
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0
answers
22
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Why does console.time/performance.measure and memory inspector don't have similar values
I'm trying to make an application that measures the times of loops with different data
This is example for memory inspector vs console.time:
Any advice or criticism is welcome from how to improve the ...
0
votes
1
answer
33
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File open problems in C
I'm coding a Priority Scheduling Algorithm on C and I have some problems with Opening a File. My laptop is M1 macbook and My Programming environment is vscode. This program is work on Terminal, but it'...
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-1
votes
1
answer
62
views
Reduce time for allocating a c++ 2D vector
The question is fairly simple. For this single line in c++,
std::vector<std::vector<double>> x_vec(10, std::vector<double>(2));
where I create a vector of size (10, 2) to be ...
- 29
0
votes
1
answer
41
views
valgrind shows memory leak in my program in c (two versions)
int main()
{
double (*arr)[COLS] = (double*)malloc(sizeof(*arr) * ROWS);
assert(arr!= NULL);
for (int i = 0; i < ROWS; i++)
{
for (int j = 0; j < COLS; j++)
{...
-1
votes
1
answer
85
views
How to handle & fix Garbage Data?
Problem state
I have a template class called Group which can access unauthorized places in memory. The member variable Group<T>::Items points to serine of locations on the heap that stores a ...
1
vote
1
answer
25
views
Is it possible to determine whether and address was obtained using sbrk or mmap?
I am developing a heap memory allocator based on Hoard for educational purposes. I know how to allocate memory using sbrk and mmap and have developed toy level allocators before.
I want to use mmap ...
0
votes
1
answer
40
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Problem with assigning value to reallocated dynamic array - maze solver
I am struggling with storing value to dynamic array, which was reallocated by realloc() function.
I am creating maze solver program and as a inner representation I want to create 1D array tile_array ...
- 85
0
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0
answers
34
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This MPI_Gatherv code not working and I don't know why
I wrote this code in C that multiplies a matrix by a vector, locally in each process(ylocal) and then the root process gathers the results in its local vector(y). I am using MPI_Gatherv because it has ...
- 1
0
votes
1
answer
52
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Freeing memory for dynamically allocated hashmap with structs as values - C
I have followed a few tutorials for hashmaps in c. From the code you can probably tell I relied heavily on this implementation which has a nice follow up video where he revisits it to show how he ...
- 3
1
vote
1
answer
88
views
realloc(): invalid old size and Aborted (core dumped) when using realloc and free in a while loop
I am working on a program that uses a linked list implemented as
typedef struct Node{
char* word;
int freq;
struct Node *next;
}Node;
typedef struct {
Node* head;
}LL;
and have ...
- 37
1
vote
2
answers
94
views
Why do we unmap memory right after copying to it
Why do we unmap memory rigth after mapping it? Isn't it that we are holding data in this address?
void* data;
vkMapMemory(device, stagingBufferMemory, 0, imageSize, 0, &data);
memcpy(data, pixels, ...
- 25
1
vote
0
answers
31
views
How does one free memory in the heap in risc-v assembly? [duplicate]
I am currently studying risc-v assembly and started to research more about the heap. In the current problem I'm solving, I'm creating a linked list by allocating space on the heap with a syscall and ...
1
vote
0
answers
76
views
Are allocatable derived type components just pointers for GNU compiler?
Consider the following minimal example:
program prog
type node
integer::val
type(node),allocatable::next
end type
type(node)::a,b
allocate(a%next)
a%val=1
a%...
- 133
1
vote
1
answer
113
views
Right way to allocate type instances containing pointers in Fortran
Consider the following minimal example:
module lib
private
type node
integer::val
type(node),allocatable::next
end type
type,public::list
integer::num=0
...
- 133
1
vote
1
answer
69
views
How to avoid reallocating an array of pointers when we dont know the exact size from start
Im trying to design a binary tree like data-struct except there is no limit on children each node can have. Now within each node I can declare node struct as such:
struct node {
int id;
int ...
- 503
-1
votes
1
answer
61
views
Memory Allocation function is not working properly [closed]
My function is not working properly. For example, when I try to add resistor called R1 with the value of 500, and then R2 with the value of 500, and then R1 with the value of 500 again, it gives me ...
1
vote
2
answers
50
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Variable doesn't get updated when I run a loop [closed]
I want to iterate through a word and print each of its characters, together with its ASCII number.
I've tried
#include <iostream>
#include <stdio.h>
using std::cout;
int main()
{
...
0
votes
1
answer
83
views
C Changing value of array of struct through reference
I asked a similar question before, when I didnt know what was the problem of my code. Just as I was recommended I will give it in a better format.
This is an example of what happens to my code.
#...
1
vote
1
answer
42
views
What is wrong with this Reflection.Emit for value conversion delegates?
Sorry for this long question but I feel I have to provide a bit more background as my issue is very specific.
Bigger picture
I am developing on a Unity tool to be used specifically for Embedded Linux ...
- 88.6k
0
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2
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23
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What are the differences between using vector and using new,delete in c++?
I would like to ask about the difference between using vector and using new, delete in C++. Both new, delete and malloc, free are used for dynamic memory allocation.
So why don't we just use vector, ...
- 3
1
vote
1
answer
63
views
Find the some smallest negative using Dynamic memory allocation in C
I'm doing my homework but there is some bugs I cannot fix
Could you please help me?
The question is using Dynamic memory allocation in C
Find the some location of smallest negative element
The ...
0
votes
1
answer
71
views
Access violation after reallocating memory
I get access violation if I'm allocating memory to list->v[list->length]
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
typedef struct {
char* denumire, * ...
0
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0
answers
21
views
Why using a pointer of a self-defined structure in the CS50 Inheritance problem
Hi here is the link of the homework description. And here is the part of the code that's relevant:
typedef struct person
{
struct person *parents[2];
char alleles[2];
} person;
const int GENERATIONS =...
- 1
0
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0
answers
20
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How to read the amount of memory block consumed by pointer? [duplicate]
There is a creation of a global accessible structure as:
struct dummy1 {
int data1;
int data2[10];
} DATA_STORE_A;
struct dummy2 {
int data1;
int data2[10];
int extended_data[20];
} DATA_STORE_B;
...
- 4,173
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3
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87
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Return string (or char *) from a C function
I need a function to return a string of various sizes.
Here is my code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
char *get_option_argument(char *arg, char *...
- 119
2
votes
1
answer
66
views
How to define different [global_allocator]s for a monolithic os kernel and its applications
We're currently working on a monolithic operating system (x86) in Rust. Our cargo workspace looks roughly like this:
project dir
|--src (contains all kernel related code, omitted here)
| |--main.rs
|
...
- 41
0
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1
answer
37
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why can i not free ctypes memory in c?
i have a python file that trys to free memory from an array created using ctypes:
import ctypes
import os
# Load the DLL
script_dir = os.path.dirname(os.path.abspath(__file__))
dll_path = os.path....
- 119
0
votes
1
answer
84
views
Problem with reallocating array during runtime in Cpp
I am trying to create an array data structure in C++ using classes. The idea is that the array has a predefined length to it and whenever there is need for extra space, the array gets reallocated to ...
- 11
0
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0
answers
39
views
Valgrind showing invalid read of size 4 when using an erase function [duplicate]
So I am writing an assignment that utilizes a vector class that I had to make that mimics the standard Vector file for c++. In my program, I am trying to filter intervals for showing more than once. ...
0
votes
1
answer
80
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Byte array and int transferring between C# and C++ in Unity DLL Integration
I am developing a Unity project where I've created a DLL in C++ to integrate with my C# scripts. The C++ function I've written is meant to receive a byte array and its size as input parameters. ...
- 9
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0
answers
96
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How to check if the requested memory chunk can be allocated?
I'm working on a C++ project where I want to utilize the TLSF (Two-Level Segregated Fit) allocator for managing memory allocations. Specifically, I need to implement a method, CanAllocate, which ...
- 1
-4
votes
1
answer
91
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C-Dynamic Memory Allocation
typedef struct {
double x;
double y;
} point;
point p1;
point* p2 = malloc(sizeof(point));
In this code where the variables p1,p2,p1.x, and p2->x are stored in stack or heap memory?
Where ...
1
vote
2
answers
79
views
Is it possible to write on memory that was moved away using memmove in C?
I'm sorry if my code is garbage but I wanted to experiment with string manipulation on an already dynamically allocated string without losing my original pointer so that when I do go ahead and free up ...
- 11
1
vote
1
answer
101
views
What's the reason for the occurrence of Segmentation fault (core dumped)?
I use C language, and apply Dynamic Programming to solve the Travelling salesman problem. There is such a problem on ZeroJudge, An Online Judge System For Beginners, but I get Segmentation fault (core ...
- 13
1
vote
0
answers
81
views
C++ templates: choice between static and dynamic allocations (a la Eigen)
Eigen, the linear algebra library written in C++, uses a clever technique: template parameters (for example the dimensions of a matrix) that are not known at compile time can take the special value ...
- 217