C++ :: How To Get Size Of Dynamic Array
Jun 12, 2013
I remember in C++, when a dynamic array is allocated, the size of this array is stored right before the array in memory. Therefore compiler knows exactly how long, when this array is deleted.
Do all compilers store the size this way? Is it a safe method to get the size of a dynamic array?
Here is a example code, it works fine on Visual Studio 2012.
#include <iostream>
using namespace std;
class dummy {
public:
dummy() {
cout<<"dummy created"<<endl;
[Code]...
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Feb 6, 2013
arrays with dynamic sizes. That being said, I'm working with a simple code which seems to work just fine, my only concern is that once I display the 'char array', not only displays the user's inputs but some extra data, symbols and what not.
why, if to my understanding the first user's input already sets the size of the array
#include <iostream>
#include <iomanip>
using namespace std;
[Code].....
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Apr 22, 2013
I'm doing an exercise which involves for the user to enter the size of the dynamic array and then enter the numbers, but then it needs to create another dynamic array with the same numbers expect if the number repeats it only has one of it. I've done the first part of the exercise but I'm having trouble with creating the new array.
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Nov 8, 2013
I'm now working on a class to handle matrices and matrix operations. I dynamically allocate a two dimensional array with its size as an input. My problem is that i need to resize the matrix structure (to fit to the size of a product of two matrices or to adjust the size after deleting a row or column for example). I make the resizing by deleting the allocated 2d array after saving its first element address to another pointer to pointer, after saving the useful data in an other array, then i use new[] operator to create a new 2d array using the same address of the old deleted array.
void My_matrix ::delete_row(int a) {
int i,j;
int buffer_row_index = -1; //note that our work is zero based, as we acess the private member of an object of the same class we are working on and we access to the array as it is (zero based) so if this variable is -1, it will be 0 when it enters for the first time and saves the data in the right position.
My_matrix buffer(number_of_rows-1,number_of_columns);
[Code] ....
I do this in a way that i think is unsafe. This code is sometimes unstable and gives an unhandled exception whose reason is unknown. I need to know whether this way is good enough or if there any other better ways.
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Jul 22, 2012
I've been in a strange problem. Im in need to have a dynamic character size, but that increases the outputsize of my program by almost 50kb. (while the program was 11kb previously).
Example:
Char One[7000]; (11kb output)
int Z = 7000;
Char Two[Z];
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Dec 2, 2013
Dynamic memory allocation in array in c programming. I am trying to make the user to choose the size of array they want to engage in the game.
However, i have remove the global variable which contribute the error to my code previously. Now I assigned all the arr individually but not using the global variable. However, i still not get the desired board i want. i still keep getting 9x9 array board.
And i also need limit the board size only from 4 to 9. And how do i do that.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <conio.h>
#include <malloc.h>
#include <ctype.h>
#include <stdbool.h>
[Code] .....
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Aug 29, 2014
I'm a little lost with this program. The idea is to dynamically allocate an array and increase its size every time a new integer is inputted by the user. I believe it is a memory leak but as we have just started learning this I'm not sure how to recognise it. Sometimes I can input as many integers as I want other times 2 or 3 before it crashes. When I can input enough values i exit the loop and send it to the sort function and mean calculator function, all works fine there except the last number inputted becomes this huge value not hexadecimal though... As such I'm at a loss as what to look at next, so here you go:
#include <iostream>
using namespace std;
void SelectSort(int [], int);
float MeanCalc(int [], int);
float MedianCalc(int* [], int);
[Code] .....
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Apr 24, 2013
My purpose is to fill a matrix with random numbers. As you can see in the code, I defined a matrix called sim_matrix (which should be filled), but the dimensions of such matrix is given by the parameters that we introduce in the constructor. Because we don't know the size of such matrix until we give these parameters through the constructor. I'd like to know how to declare such matrix, or how to modify the size,...
The header of my file MonteCarlo.h is:
/* MonteCarlo.h */
#ifndef MONTECARLO_H_
#define MONTECARLO_H_
using namespace std;
class MonteCarlo {
public:
MonteCarlo(int n_paths, int n_simulations);
[Code] ......
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Mar 12, 2012
I am designing an application in which I need to deal with many different variables in which different sequences of bits are stored. I have very strict memory requirements so I decided to use the boost::dynamic_bitset data type which works very well in my scenario as I need to dynamically allocate/deallocate/resize the variables.
The only problem is that I am not able to change the size of the blocks in which the dynamic_bitsets are stored.
I mean, even if I specify the blocks should be "unsigned char", I always obtain 32 bytes allocation by sizeof function, even if the variable is empty.
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Jan 4, 2013
I'm writing a program in which I have to use a matrix to represent a file in code. because it's a file, the size of the matrix is undefined, and therefore the matrix has to be dynamic. I found out that my compiler doesn't like dynamic multidimensional arrays, so I was thinking of this matrix as a dynamic (monodimensional) array of other dynamic (monodimensional) arrays. My program (and thus this example) uses unsigned chars.
unsigned char variable=something;
unsigned char**matrix=new unsigned char*[lenghtOfMainArray];
for(int rowNumber=0;rowNumber<lenghtOfArray;rowNumber++)
{
[Code].....
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Mar 13, 2013
But it can the other way around
Code:
static_Array= dynamic_Array;
dynamic_Array = static_Array;
The second statement works and i'm able to print out both arrays with equal values but with the first
[code] static_Array = dynamic_Array;I get incompatible types in assignment of 'int*' to 'int [7]' is the error I get [/code]
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Jan 10, 2015
Write a program using user-defined function which accepts an integer array and its size as arguments and assign the elements into a two dimensional array of integers in the following format: If the array is 1,2,3,4,5,6, the resultant 2D array is
1 2 3 4 5 6
1 2 3 4 5 0
1 2 3 4 0 0
1 2 3 0 0 0
1 2 0 0 0 0
1 0 0 0 0 0
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Jun 27, 2014
I'm wondering if it is possible to pass a 2d array to a function where the size of the array is not known at runtime.
I've tried
function ( array[][6] ) ;
But the size of the array has to be constant so it cannot be declared later.
I've tried using a template but you still have to declare the size of the array at runtime. Is this even possible at all?
The only other way I can think of is using a dynamic 2d array but how to create one and manipulate it.
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Jul 15, 2013
Code:
Int** d = malloc( ROWS * sizeof(int*));
for (i = 0; i < ROWS; i++)
d[i] = malloc(COLS * sizeof(int));
fx(d);
My question is, in a function declaration, why do I not have to specify the number of columns. How is this different than when I pass a static 2D array to a function, in which I must declare the function parameter with the number of columns.
Code: void fx(int d[][COLS]);
VS.
Code: void fx(int **d);
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Sep 13, 2013
So this is the code I have so far, I didn't know it had to be a dynamic array so how would I Utilize dynamic array allocation to size the modal array
#include <iostream>
using namespace std;
int main() {
const int arraySize = 25;
const int patternSize = 10;
[Code] ....
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Mar 4, 2014
I need to create dynamic array or map. for example
CString *a1;
CString *a2;
CString *a3;
it minimized to using for loop.
for (int i=1;i<=3;i++) {
CString s="a"+"itoa(i)"
CString *s;
}
Something like this. its same as map concept.
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Nov 14, 2013
I need to confirm that this problem cannot be solved without a pointer. Namely I need to read the rows and columns number from the user cin >> m, n and then use to declare an array int A[m][n];
However as m and n are not constants I am not able to do that. Is there a workaround? The following is the solution I came with BUT using a pointers which should be not the case.
// solution with using pointers as "int A[m][n]" does not work for me!!!
void TwoDimensionalArrayFunc(){
int m = 0;
int n = 0;
// instruct the users to enter array dimensions
cout << "Please insert value for m:";
cin >> m;
[Code] ....
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Dec 26, 2012
I need to write 2 functions:
1. MyMalloc
2. MyFree
___________________________
I have a 1000 bytes global array (which did not dynamic allocated).
I need to make "dynamic allocation" from this array.
For example - MyMalloc(50) ---> The program will allocate 50 bytes OF THE ARRAY'S SIZE.
------
MyFree(pointer) ---> I need to check if the pointer is in the array and free the space.
It should be managed by blocks. The array should also contain the manage variables (for me).
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Dec 13, 2013
I am trying to figure out copy constructors for a dynamic array and I am definitely missing something. If I go into the copy constructor routine during debug, the values appear to be correct but they don't percolate up to the newly created object. I'll post a portion of the code below:
Code:
// include header files for the classes that are being used
#include "stdafx.h" //
NOTE: THis reference must be added to all cpp files in Visual Studio Express 2013
#include <iostream>
#include <string>
#include <cstdlib>
#include <map>
using namespace std;
const int ARRAY_SIZE_DEFAULT = 32;
class vectorOfInt {
public:
[code]....
The size of c is 0. Values of a were not copied to c, although they appear to do so within the copy constructor routine.
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Feb 14, 2013
Code:
public void dam_data_setup() {
// fill list
damgtype.Add( den1);
damgtype.Add( den2);
damgtype.Add( da1);
damgtype.Add( da2);
damgtype.Add( db1);
damgtype.Add( db2);
[Code] .....
This is a genetics program and is to parse the source array and write all possible combinations to a new array. All sections but dilute work correctly. For some reason the dilute's Boolean is not testing true when it should. This is causing data corruption.
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Jun 11, 2013
I have a little problem with one of my functions. The function purpose is to get a number (n) and create an array (size n) with pointers to strings (each string length is 20 chars) and i don't know why but during the debugging i get a <bad ptr> message and this message :
CXX0030: Error: expression cannot be evaluated
This is my function:
Code:
char** getlist(int n) {
int i=0;
char **arr;
arr=(char**)malloc(sizeof(char)*n);
if (arr==NULL)
[Code] ....
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Jan 29, 2014
I am trying to create an dynamic array (lno) This array will store addressess of different Linked list. What exactly I want is:- Take N Number of Linked List user want to create> eg. 2 now It will create 2 linked list for which I am trying to allocate memory.
Code:
struct node{
int data;
struct node *next;
}
first;
lno[0] Node 0's first address stored in ln[0] lno[1] Node 1's first address stored in ln[1] Here is the code in which I am facing problem with error Illegal structure Operation
Code:
#include<conio.h>#include<stdio.h>
#include<stdlib.h>
struct node
{
int data;
struct node *next;
};
[code]....
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Jul 27, 2013
I coded a program that takes some strings and lexicographically orders the strings and its substrings. I have used dynamic memory allocation technique and its working fine for all strings without consecutive same alphabets.I use a list in which a string is placed in its exact position by moving the others right.
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <conio.h>
[code]....
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Nov 22, 2013
I'm having a bit of trouble trying to delete elements in a dynamic array of objects. I tried to delete elements by shifting that particular element and the ones that follow over one element and then assigning the last one to NULL.
cin >> input;
while (input != -1 || k == 7) {
for(int i = 0; k < numberOfRecords; i++) {
if (input == records[k].id) {
[Code] .....
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Apr 22, 2014
I made a resize function for my dynamic array template class that goes as follows. Note that the private member variables are T* arr, unsigned used, and unsigned cap.
template <class T>
void darray<T>::resize(unsigned size) {
if (size > cap) {
T* temp_arr = new T[size];
[Code] ....
Whenever I use this function to increase the size of the array, it will work the first time I need to use it, but after that, Visual Studios will trigger a breakpoint at line 14, and if I continue past the breaks, I eventually get _CrtIsValidHeapPointer(pUserData) assertion failure.
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May 8, 2014
I am trying to pass a dynamic array to a function which will:
- Copy the contents of the array to a temporary dynamic array
- Change the array passed in to one size bigger
- Copy the elements from the temp array back into the newly changed array
- Insert an item into the last spot of the array
Here is my code:
#include <iostream>
using namespace std ;
void make_array ( int Old [] , int & old_size , int toInsert ) ;
void zero_array ( int arry [] , int arry_size ) ;
void print_array ( int arry [] , int arry_size ) ;
[Code] .....
The output seems like a memory address but is just a very large number, what have I done incorrectly to cause this?
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