Questions tagged [malloc]
The malloc function performs dynamic memory allocation in C and is part of the standard library. Use this tag for questions about usage, behavior and implementations of malloc.
malloc
9,303
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Difference in Memory Usage Between malloc and new in C++
I'm observing a difference in the total memory allocation when using malloc versus new in a simple C++ program, as reported by Valgrind. Below are the two versions of my program and the corresponding ...
- 13
1
vote
1
answer
28
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Can't put values together into struct that is initiated by pointer and malloc [duplicate]
Just a simple struct called person, inside I need to store name and age. I'm trying to dynamically allocate memory for my struct.
Without using pointer:
#include <stdio.h>
#include <stdlib.h&...
-6
votes
2
answers
71
views
malloc(): corrupted top size on deleting an entry from binary file [closed]
I AM CREATING A SCHOOL MANAGEMENT SYSTEM . WHEN I TRY TO DELETE A STUDENT AFTER ADDING ONE I AM GETTING "malloc(): corrupted top size" ERROR .CANT FIND THE REASON.I AM A BEGINNER , HELP ...
- 3
0
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0
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61
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+50
Large allocation metadata is causing fragmentation and wasting DRAM in jemalloc when using extent hooks
I am writing a simple custom extent allocator that returns extents from a pre mapped area (this way I can explicitly control the mapped area -- and the allocations in it). I am using the dev branch of ...
- 99
0
votes
1
answer
53
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How to get rid of C6387 warning on call to fwrite function?
In Visual Studio 2022, I am getting the following warning when I call fwrite.
Warning image C6387
It says: C6387:'fout' could be '0': this does not adhere to the specification for the function 'fwrite'...
- 3
0
votes
0
answers
17
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Initializing an array created with malloc with arbitrary values
I need to create large float arrays using malloc, to be able to free the memory when I don't need the array anymore.
The values are arbitrary, meaning they are not all zeros or ones, much more random ...
0
votes
0
answers
69
views
How do I solve "realloc(): invalid next size" error?
Here is the section of code where my program crashes:
if (fromNode != toNode) {
pthread_mutex_lock(&mtxs[fromNode]);
g->out[fromNode]++;
if (g->in[toNode].index == g->in[...
- 11
0
votes
3
answers
87
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Error in assigning values to memory location with for loop [duplicate]
I have just entered the world of C programming, and I'm currently learning how to use malloc & free.
I've written a short excercise code to printf the string entered with scanf, and I am having ...
- 27
0
votes
0
answers
15
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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 ...
4
votes
2
answers
125
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Function to clear allocated memory is not working
I'm trying to make a DTC in C. This is the structure of the nodes:
typedef struct node {
int value;
struct node *lower;
struct node *higher;
} node;
To free the memory allocated using ...
3
votes
2
answers
148
views
Malloc sometimes fails immediately after a free
I want to test my code in low memory situations.
I wrote this function with setrlimit to limit the available memory :
unsigned short int oom_enable = 0;
char* _oomfill = NULL;
uint32_t oom_setup(...
0
votes
1
answer
35
views
How to know heap overflow point?
I'm attempting to write a program that determines all palindrome within a given range. My program calls a function (number of digits) that returns the size of an integer (ie. 400 would be 3 as it has ...
- 67
0
votes
1
answer
103
views
How to free memory for an array allocated by malloc?
I have 2 variants of code:
1st:
void PrintMem(const int* memarr,const size_t size) {
for (size_t index = 0; index < size; ++index) {
std::cout << '<'<<(index+1)<<&...
- 1
1
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1
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78
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wrong values when displayed : C pointer or malloc issue?
My program multiplies a matrix 1 by a matrix 2. The matrix 3 is the result.
I can display matrix 1 and matrix 2 with the correct values but I am not able to display though the same function the ...
- 199
0
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3
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116
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Using the malloc function once initializes all uninitialized variables with a 0
The malloc function is not supposed to initialize any value to any variable it is used on, like the calloc function does. Why then do I keep getting the initialized value of even other varibales to ...
