Copy elements of pointer.

[hahacprog]

I tried to understand pointers and I cant figure out how to copy the elements of the array that the pointer point to.

int main(){

	char a[3] = {'a', 'b', 'c'};

	char p[256];
	char copy[256];
	char *q[256];

	p[0] = *a;
	p[1] = *(a+1);
	q[0] = a;
	
	cout<<p[0]<<endl;
	cout<<p[1]<<endl;
	cout<<q[0]<<endl;

}

so when i print the q[0] it will show abc as the result. is there any way to copy the q[0] element by element into another array. so it will create another copy of array like a[3].

[Lachlan Easton]

p[0] = *a;
p[1] = *(a+1);

Should be (or is equivalent to at least):

p[0] = a[0];
p[1] = a[0];

From there, do you know what a for loop is and how to use it? If not then you should be learning about basic control structures before pointers.

is there any way to copy the q[0] element by element into another array.

You started doing this for the first two elements (you copied 'a' and 'b' into p)

[hahacprog]

Thanks for the reply. I'm quite familiar with the for loop. I understand that i had copied the first two elements into p, and the q is pointing to the whole array of a. Is it possible to copy into array(like i did to p) from the pointer q?

[MiiNiPaa]

Yes, it is possible. Pointer to first element of the array can be used just like array:

int a[10] {0, 1, 2, 3, 4, 5, 6 ,7 ,8 9,};
int a_copy[10];
for(int i = 0; i < 10; ++i) {
    a_copy[i] = a[i];
    a[i] = a[i]*2 + 1;
}
int* p = a;
int p_copy[10];
for(int i = 0; i < 10; ++i) {
    p_copy[i] = p[i];
}

[keskiverto]

The q is not a pointer! It is an array of pointers. The q[0] is a pointer that points to the first element of array a.

[akash16]

Hi,
Array should be of size 4 at line number 4.

For your que :
"is there any way to copy the q[0] element by element into another array. so it will create another copy of array like a[3]."
Please have a look below sample code:

int main()
{
	char a1[4]= {'a','b','c'};
	char* arr[30];

	arr[0] = a1;

	char a2[4];
	a2[0] = *arr[0];
	a2[1] = *(arr[0]+1);
	a2[2] = *(arr[0]+2);
	a2[3] = '\0';

	cout<<a1<<endl;
	cout<<arr[0]<<endl;
	cout<<a2<<endl;

	getch();
	return 1;
}