C++ :: How To Check And Allocate Memory From Given Address Range
Jan 2, 2013
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.
void * allocMemoryInMyHardware(int numberOfBytesToAllocate);
which returns a pointer to the allocated memory chunk, or null if unable to allocate.
C library calls like malloc are not allowed.
1) How to allocate memory from given address range.
2) How to check whether this required memory space is available or not for allocating
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Jan 13, 2013
what i want to do is if memory allocation fails it display a message shown in the example but its not working
vehiptr = new VEHICLE[vnum];
if(vehiptr == 0)
{
cout<<"Failed to Allocate Memory"<<endl;
return main();
}
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Oct 25, 2013
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..
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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.
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Mar 8, 2014
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?
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Sep 24, 2014
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..
void cardInit(card *deckPtr) {
card *deckHome = &deckPointer[0];
ifstream fin;
char *finName = new char[13];
cin >> *finName
fin.open(finName)
[Code] ....
Its a pretty simple program..and my dynamic memory works for the file name, but I cant figure out why it doesnt work for structs?
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Nov 5, 2014
There is a part in the lesson that explains how malloc is used to allocate free memory to a pointer and gives us 2 examples:
Code:
float *ptr = malloc( sizeof(*ptr) ); and Code: float *ptr;
ptr = malloc( sizeof(*ptr) );
From my logic in the first case we allocate the memory to *ptr and in the second to ptr.
It's a bit confusing, am I missing something?
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Jun 13, 2014
Consider this program:
Code:
// sb_string class v1.04
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct sb_string {
[Code] ....
And here is the output I got:
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.
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Aug 30, 2013
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:
#include <iostream>
#include <array>
#include <iomanip>
#include <string>
[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.
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Apr 9, 2012
I use the array of Radiobutton,string,.. in my project. How i can destruct these array from memory,because i see the stackoverflew exception.
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Jan 24, 2013
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.
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May 11, 2012
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?
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Feb 23, 2015
In my program I have a range check setup in the class I call from main, but when I run it and put in a value > or < than the min/max it just calculates anyway. Where have I made a mistake?
Heres the Main
#include "box_class.h"
#include <iostream>
using namespace std;
int main() {
double length;
double width;
double height;
double volume;
[Code] ....
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Jul 13, 2013
Now I have to write a code which would determine whether an Email address is valid or not.
In my exercise a valid address should look like this : ___@___.___.il (___ for any letters)
E.g. Valid address:
something @ something . something . il Invalid: tami @ jce . ac . uk
(without spaces of course)
Code:
#include <iostream>
#include <string.h>
using namespace std;
int isValid (char s[]) {
int length=strlen(s), ind1=0, ind2=0;
[Code] ....
It doesn't work well. It says both addresses are wrong when the 1st one isn't.
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Jan 3, 2015
I'm having an issue coming up with an if() statement to check if a word match the one in the value of a pointer's address. So far the best I've come up with only matches the first letter of the words, you'll find it in the code below.
#include"Header.h"
int Colour(struct MyStruct *ArrayPointer, int ArraySize) //ArraySize = 3 for this run. {
int ColourCount = 0;
for (int i = 0; i < ArraySize; i++) {
[Code] ....
An example run you can see in attached pic.
I want to have an if statement that only accepts "Red" and not the occasional "Ravaged_Anus".
I'm using MVS Express 2013, .c source files, and the C++ compiler.
Attached image(s)
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Nov 20, 2012
I have written a C program without variable. And I want to print the value at that memory location.How to print that value?
code is like:-
int main()
{
printf("Enter value:");
scanf("%d",1245024);
/* how to print the value here */
return 0;
}
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Jan 14, 2014
I am working on something that requires the memory address of my computers workload.. collect the trace files? and what trace file as well..
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Sep 30, 2013
Pointers point to an address in memory. What if I used 3 pointers: 2 to mark the first/last nodes, and the third to mark the current node being referenced? I would wrap it in a class (to make the memory management automatic, of course), but is this practical?? maybe some pseudo code will get the juices flowing:
template<class type>
class supercondensed_list{
public:
supercondensed_list();
~supercondensed_list();
[code].....
Any things I should take into consideration? I'm not exactly the most experienced with pointers, and manually managing memory, but I think it's worth trying. If this works, then my programs should, in theory, be 100% memory efficient.
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Sep 9, 2013
I've recently been reading tutorials on arrays and their aquaintance with memory addresses. So, I completely understand how an array's name, when defined, is a constant pointer to its first element's address.
My problem, however, lies with characters, and how they are basically arrays except with a null terminator for the last index. What I've come to undestand, is that, when defining a character variable, each 'character' has a memory address it is associated with.
For example:
char name[] = {"Hello"}; // | 'H' | 'e' | 'l' | 'l' | 'o' | '/0' |
An address holds the value of 'H'.
An address holds the value of 'e'.
An address holds the value of 'l' and so on.
I have come to believe this is false, however. Mainly from a simple std::cout command.
std::cout << &name << std::endl; // attempt 1
std::cout << &name[0] << std::endl; // attempt 2
The first attempt, as I assumed, should print the address of the first element.
The second attempt, as I assumed, did not. I figured, &names[0] would print the address of the first element, which should have been the same as &names.
So, this brings me to my question, are characters formed of constant addresses, or are the address of individual characters not reachable?
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Apr 29, 2013
What I'm trying to do is:
int *p;
someType memoryLocation;
cout<<"Enter your memory location: ";
cin >> memoryLocation;
p = memoryLocation;
cout << *p;
I was just messing around with some code, and was curious to if this was possible.
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Jun 30, 2014
The results of my code is supposed to be very simple: return the 2 integers and then their sum. However, it's doing returning the first value, then an address in memory(rather than the 2nd value), and then the 2nd value(rather than the sum). Here is the code:
#include <stdio.h>
#include <stdlib.h>
struct calculator{
double num1;
double num2;
double result;
[Code] .....
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Sep 12, 2013
I made a text file. I can do all File I/O functions in c. no problem! except that "I want to get the memory address of the beginning of that File", so that I can access each character of the file by incrementing memory address.
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Jun 3, 2013
I have an integer pointer and i want its address without allocating memory,
main() {
int *a;
cout<<a;
}
This is giving 00000000 and its but obvious. Now if i use address of a (&a) along with *a,
main() {
int *a;
cout<<a;
cout<<&a;
}
'cout<<a' gives me a constant address but 'cout<<&a' gives me different address.
what is the reason behind & and why behaviour of 'cout<<a' changes when using with &.
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Jun 22, 2013
Suppose I have two classes, MyClassX and MyClassY, each with two member variables, as defined below. I create an object instance of each class, and then create a pointer to each member variable for each object:
Code:
class MyClassX
{
public:
int a;
double b;
MyClassX(int _a, double _b)
[code]....
After converting the hexadecimal to decimal, it appears that with MyClassX, pxb is 8 bytes from pxa, whereas for MyClassY, pya is only 4 bytes from pyb. This makes sense for MyClassY, because the first member variable to be stored is an int, and so will occupy 4 bytes. However, why should this be any different for MyClassX, which also has an int as the first member variable, so shouldn't this also occupy 4bytes?
The reason I have come across this problem is that I am looking into streaming objects to memory and then loading them again. (I know boost can do this, but I am trying it out myself from scratch.) Therefore, this is causing an issue, because I cannot just assume that the size of memory occupied by an object is just the sum of the sizes of its member variables. MyClassX is 8 bytes larger than MyClassY, even though the intuition is that it should only occupy 4 bytes more due to a double being replaced by an int.
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Jul 8, 2014
When declaring char array[10], memory is allocated for 10 1-bit memory locations. Is extra memory allocated for storing the address of array[0]? In expressions, is array equivalent to a pointer constant or is it an identifier for a memory cell containing the address of array[0]? In other words, is array a variable or an alias for &array[0]?
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Jul 26, 2012
Try to implement overloading << operator. If I done it void then everything work fine (see comment out) if I make it class of ostream& then the operator return to me some memory address.
Code:
#ifndef Point_HPP // anti multiply including gates
#define Point_HPP
#include <sstream>
class Point {
private:// declaration of private data members
double x;// X coordinate
double y;// Y coordinate
[Code] .....
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