Remove zeros from array

[TunaPete]

I want to remove all the elements that are zero from an integer array. If I understand correctly that is "impossible" to do on the original array since it MUST have five elements after the declaration? Therefore I have to use another array c? :

//OBS the code works!
int b[5] = {0, 1, 0, 2, 3}; //For example
    int numOfNoneZero = 0;
    for(int i=0; i < 5; i++){
        if(b[i] != 0)
            numOfNoneZero++;
    }
    int c[numOfNoneZero];
    int j = 0;
    for(int i=0; i < 5; i++){
        if(b[i] != 0)
            c[j++] = b[i];
    }

    for(int i= 0; i < numOfNoneZero; i++)
        cout << c[i] << endl;
    delete[] b;

At the end I delete b. Is that enough to free the memory? But b still exists in some way? What if I want to completely destroy b for all eternity?

Are there any pre-written routines in C++ that could have done the work for me?

[tummychow]

You do destroy b*. The memory to which it points is removed. You can't just obliterate a stack-allocated variable, though. It would have to go out of scope like this.

{
    a variable is declared here;
}
but it no longer exists here
even if the code block has no connected statements like ifs

You would be better off using an STL container like a vector.

[Duthomhas]

Yes, you cannot delete[] something that was not allocated with new[].

In the case of static local arrays (what you've got), it is typical to keep track of how many elements you are using in the array:

int b[5] = {0, 1, 0, 2, 3};
int bsize = 5;

In order to "remove" the zero-valued elements, you need to move them to the end of the array and adjust the 'used element' count:

b == {1, 2, 3, 0, 0}
bsize == 3

In practise, it is not necessary to actually preserve the element(s) being removed, so your final result may look something like:

b == {1, 2, 3, 2, 3}
bsize == 3

Hope this helps.

[TunaPete]

Thanks for the help guys, it does clear things. But I've realized I need a book after all. This is not as easy as I hoped :). Trying to translate a matlab code to C++. And in matlab the line a(a==0)=[]; would have been enough (not saying matlab is better obv).

[firedraco]

Yeah, matlab is (kind of obviously) made for math stuff like matrices, arrays, and stuff like that. C++ has a bias towards systems programming, so it contains things like pointers, strings, etc.

[qtpan]

You can use two dynamic array to do that thing.
But in your code,i used one static and one dynamic.HTH

#include <iostream.h>
#include <conio.h>

main()
{
int ar[5]={0,1,0,2,3};
int *ptr1;
int ctr,x=0,nonzero=0;

for(ctr=0;ctr<5;ctr++)
	{
   	if(ar[ctr]!=0)
      	{
         	nonzero++;
         }
   }
ptr1=new int[nonzero];

for(ctr=0;ctr<nonzero;ctr++)
	{
   	if(ar[x]!=0)
      	{
          ptr1[ctr]=ar[x];
         }
      if(ar[x]==0)
      	{
         	ctr--;
         }    x++;
   }

for(ctr=0;ctr<nonzero;ctr++)
	{
		cout<<ptr1[ctr]<<endl;
   }

   getch();
}