how to create adjacent arrays in memory

[sudeepta]

Hi i'm new to programming. I wanted to create two integer arrays which are adjacent in memory. i had written the following code, but i'm getting segmentation fault when i run it.

#include<iostream>
using namespace std;

void printarray(int* a,int size)
{
for(int i=0;i<size;i++)
cout<<a[i]<<endl;
}

int main()
{
int a[3]={0,1,2,}; //the first array
int* pa;
pa = &(a[2]);
pa++;
int* b = pa; //the second array


for(int i=0;i<3;i++)
{
b[i]=i+2;
}
printarray(a,3);
printarray(b,3);

}
any help would be greatly appreciated

[exception]

What do you want to do? I mean, *why* do you want them to be adjacent? Most likely, there is a better solution. If not (and please *ONLY* if not): you make one array twice the length you need (int x[6]) and then point to the location you want (int* a1=x; int* a2=x+3;)

[bnbertha]

You are running off the end of the array.
I've reproduced your code here using code tags to get the line numbers

#include<iostream>
using namespace std;

void printarray(int* a,int size)
{
    for(int i=0;i<size;i++)
    cout<<a[i]<<endl;
}

int main()
{
    int a[3]={0,1,2,}; //the first array
    int* pa;
    pa = &(a[2]);
    pa++;
    int* b = pa; //the second array


    for(int i=0;i<3;i++)
    {
        b[i]=i+2;
    }
    printarray(a,3);
    printarray(b,3);

}

You only have one array, the one declared on line 12. pa and b just point to parts of that array.
On line 14 you set pa to point to the last element of array a[], then on line 15 you move it past the end to point to what could be anything (effectively random data). Then you set b to point to this random data.

Then you have your problem code, the for loop at line 19. You have no idea what is in the memory b points to (it could be critical data) but you are attempting to overwrite it. The operating system has detected you trying to write to an area of memory you are not allowed to, and has terminated your program.

To create your two adjacent arrays, I would create one that is double the size you need and use a pointer to point half way using it as the second array

int a[6] = {0,1,2,3,4,5};
int *b = &a[3];

It's the only way to reliably get adjacent arrays.

EDIT: beaten to it :)

[sudeepta]

@exception
Thanks..actually theres no particular reason why i wanted to do that,just wanted to see if its possible

[sudeepta]

thanks bnbertha...i got it now