Reallocate Memory

[gamiR]

In my C++ programme I want to use dynamic array which will be modified easily.i.e. Consider the array of int datatype .Initially Its size is asked to user.If array becomes full and I want to add some more element how the size of that array will be increased.Please suggest some function in c++ which can do this.I know about New operator.Will it be used for reallocation of memmory i have doubt about it.

[dargueta]

No. Try using realloc(). You need to include malloc.h for it. I'm not sure if it works with the new operator. In that case, you'll need to allocate memory like this (someone else correct me if I'm wrong, please):

#include <malloc.h>
#include <iostream>

using namespace std;
.
.
.
int *myArray;
int arrSize = 10;

//use calloc to allocate arrays, and malloc to allocate single blocks,
//like for classes and structs. I'd use the new operator for classes,
//though.

myArray = (int *)calloc(arrSize,sizeof(int));
if(myArray == NULL)
    cout << "Allocation failed." << endl;
.
.
.
//reallocate:
arrSize = 15;
int *temp = (int *)realloc(myArray,arrSize);
if(temp == NULL)
    cout << "Reallocation failed." << endl;
else
    myArray = temp;
.
.
.
free(myArray);

[gamiR]

But suppose i allocated memory to array using New operator.And now use realloc function will it work?

[Aereshaa]

No. The new operator may allocate memory a different way, so even if it works on your system, it might not work on other peoples'. Better to allocate using the function malloc() and deallocate using free():

int * array = malloc(10 * sizeof(int));
array = realloc(array, 15 * sizeof(int));
free(array);

[gamiR]

Thank you for your guidance .So C++ has this drawback.We have to use malloc & realloc .

[WingedPanther]

A better option is to use a vector instead of an array. You can indicate the initial size, and it will automatically grow as needed if you exceed that size. That will remove the need to handle memory allocation yourself.

[MeTh0Dz|Reb0rn]

Linked lists are good for this type of thing to.

[dcs]

Originally Posted by WingedPanther

A better option is to use a vector instead of an array. You can indicate the initial size, and it will automatically grow as needed if you exceed that size. That will remove the need to handle memory allocation yourself.

Aye.

[Anirban Chakraborty]

When it is specified that one has to use "dynamic array" you are not supposed to use Linked List. Guess that is an assignment.
So better option is that one uses vector. Moreover one won't have to get bothered about methods and pointers of Linked List.

[MeTh0Dz|Reb0rn]

What are you talking about, of course you can use linked lists for dynamic memory assignment.

Are you serious?

After reading your post, I'm going to slightly retract that statement as I now think that maybe that was a comment on your assignment...