C :: Function That Allows To Allocate Memory To Variable
Nov 8, 2013
I am trying to make a function that allows me to allocate memory to a "mem" variable and setting each of its chunk's status to FREE. FREE is defined as 0. Below is my code of the function.
Code:
int allocate(mem *mm, int num_chunks, int chunk_size) {
int i;
mem *temp;
if((mm = (mem *) malloc((num_chunks + 1) * chunk_size)) == NULL){
perror("Failed to Malloc
[code]...
mem; If my function works the way it should, it should print out five 0 because that is how I set them in the function, but this is not the case. I've looked at my function for 2 hours, but I could not figure out any logical error. Now, I think my problem lies with my limited knowledge of pointer arithmetic. On the other hand, when I insert 1000 as the second argument into my function, it gives seg faults, which is not the case for smaller values like 5, 10, 15, etc.
So my assignment is to create a program that calls for a function in main that dynamically allocates an array[3] and then have pointers with multiple levels of indirection and pass them by reference so they are not lost after the function. Here is my code:
Next part is to ask user for two non-negative numbers and then get the length of those numbers and create an array. for the size of each number they input. Then to separate those numbers and add the cross-sums.
I'm currently learning templates -- & my logic is in a knot with what I am trying to do which is the following:
-Create a function name load -Accepts a filename (the filename is a text file of integers) -Open the file -Create an array(dynamically allocating an array) filling it with the elements read in from the file & returns the array(so that the return type of the array is a pointer to the element type of the array).
//Header file: #ifndef BUBBLE_SORT_H #define BUBBLE_SORT_H #include <iostream> template <typename T> void load(std::string filename, T *&arr, int *size);
[code].....
how to allocate memory when it comes to using templates..
I’m writing an application for raw image processing but I cannot allocate the necessary block of memory, the following simple code gives me an allocation error.
double (*test)[4]; int block = 32747520; test = new double[block][4];
off course with smaller block size (i.e. int block = 327475;) it works fine. Is there an allocation limit? How it is possible to deal with big blocks of memory?
I CANT use std::string, classes, constructors for this project. I am required to use this archaic method of c-style strings with dynamic memory allocation occurring outside the struct.. i know its not the best way to go about this, but there's nothing i can go. I have a struct:
struct card { char *suit; char *rank; int cvalue; }
I've created a pointer of size 52 for my deck
card *deckPtr = new card[52]; card *deckHome = &deckPtr[0];
I then try to use
for(int i=0;i<52;i++) { (*deckPtr).suit = new char[8]; (*deckPtr).rank = new char[7]; deckPtr++ } deckPtr=deckHome;
I am essentially trying to fill in these arrays from a card file, but I cannot make it past running the program, i get sa seg fault which I dont understand why.
I dynamically allocate memory in my card read in function..
Code: [harshvardhan@hari-rudra] ~/Desktop% gcc49 -o test test.c [harshvardhan@hari-rudra] ~/Desktop% ./test -before Value of len = 1 (in_function)-before Value of len = 1 (in_function)-after Value of len = 1
-after Value of len = 1 I was trying to make a little easier to work with string. Once the memory is allocated by malloc via sb_init() function, the sb_massacre function wasn't working to deallocate the memory. I had used multiple versions of gcc and clang but the result is same.
A special hardware unit with some storage in it is connected to your computer and is memory-mapped so that its storage is accessible in the address range 0x55500000 – 0x555fffff. You want to interface this hardware unit to your C++ program so that dynamic memory is allocated in this hardware unit, not in your computer’s memory. Implement a class MyHardwareMemAllocator which has the following function.
I created a structure containing two variables of type char.
i.e. char name[64],char details[128];
And a pointer to structure now when I write this name and details to file and now I want to change the particular name.
i.e. To modify then if the stored file name is greater than the entered name then it is erasing the next record line also I need to allocate some memory.
I have a question about the KLU library for LU factorization of sparse matrices. The KLU library accepts a pointer to a memory allocator function, by default it is malloc(). Then it uses this pointer to allocate the memory required.
I want to extend the library and I now have object of classes. I want to use the operator new instead of malloc to allocate the memory. In the same time I want the new operator to call the constructors of the objects. Is there a way to do it?
So, I've made programs like Prime number searchers and such. But the problem is if I use an int or long int variable for the program I am limited by the variable size. I can't search through numbers larger than their memory size. So my question is: Is there a way to allocate memory to a single variable, NOT AN ARRAY, so I can make a variable as many bytes as I want?
How do you store a variable in memory so that it isn't changed when the program closes? I don't have any experience with this and am just wondering how it is possible. I am creating a program and want it to store your preferences and scores. In a simple program, everything is just reset and I don't want this for my program. How do I store a variable so that it stays the same, but can be changed even when the program is turned off?
recently I developed a class header only in C++ to deal with byte arrays. Since I developed programs in other languages that had some libraries to dial with byte arrays, I developed one that the syntax is very similar to other languages.
Since I'm not very familiar with memory management, I was concerned about somethings I've read about (ex: memory fragmentation).
The class is intended to be used as part of comunication protocol in a webserver, byte arrays are created and destroyed a lot. Should I use pools? Is there a better practice? Am I doing everything wrong (laugh)?
For those who wants to see the entire class: [URL]
If I have a pointer variable indicating memory location in which we have stored what user entered and the pointer is of type volatile if the user gives the character 'a' twice , then this character will not be fetched twice from the memory but only when the character is changed???
This is the one meaning of the volatile? the other is that the value will be changed without the program itself change it?
I want to store few different functions to a variable for different structs/classes and then call it later using that variable, is it possible? something like
struct item { int ID; int special; // for function };
item Key; Key.special = UseKey(KEY_KING);
// now when I want to call function "UseKey(KEY_KING)" I want to use "Key.special", like this
Write a program that dynamically allocates an array large enough to hold a user-defined number of test scores. Once all the scores are entered by the user, the array must be passed to a function that sorts them in ascending order. It must use another function that calculates the average score. The program should display the sorted list of scores and average with appropriate headings. The program must use pointer notation instead of array notation. Validation: Do not accept negative numbers for test scores; keep prompting the user for a new grade. Do not accept negative numbers for the number of scores the user wants to enter.
#include <iostream> #include <iomanip> using namespace std; // Function prototypes double getAverage(int*, int); void sortScore(int *,int );
[Code] ....
I have no errors in my code but when i run it and i enter a positive interger it just goes into a loop to enter a positive number.
If I have understood well the above code can be a typical example that decribes a memory overlap. Some of data to the destination (str + 2 ) will be copied before its copy.
According to the above example I think there is no quarantee even the restrict to the pointer that we won't have overlap.It is legal to use the same pointer and not other in order to have access on the data.So for this the behaviour is not undefined right?
But how memcpy works? I mean I am taking
Code: HEELLOIR as output rather than Code: HEEEEEIR So the behaviour due to overlap is undefined?
The const on const void * restrict s2 denotes that data can't change from s2 itself?
