copy one array to another

[MRKSalman0349]

hey guys i need a litle help
why this code will not work??
plz help me
a = b works but it is a shallow copy ??

how to make a deep copy of this ...plz help

  void copy(int *a, int *b, int b_size) {
     if(b_size == 0) return;    
     *a = *b;
     copy(++a, ++b, b_size-1);
}

[LB]

What specifically does not work? Does it crash? Does it break the speed limit and get a ticket? Does it steal your wallet? You need to be specific.

[MRKSalman0349]

when i call this function all the code after this function is skipped and the program closes with a return value that is very large

[LB]

Have you tried debugging it? At the very least, put a statement to output the parameters when the function starts.

Do you need this function to be recursive? If not, you should just use a normal loop, or use std::copy.

[MRKSalman0349]

no i need to solve it via recursion

[MRKSalman0349]

yes the function is called but i think there is some problem......
i wrote an output statement and that was shown to the console but the rest of the function does not

[cire]

How do you define the arrays which you feed to copy and how do you determine the initial size fed to the function?

[abhishekm71]

Please show the code for your calling function.

[MRKSalman0349]

#include <iostream>
#include <cstdlib>

using namespace std;

void copy(int *a, int *b, int b_size) {
	cout << "Copy Function called \n";
     if(b_size == 0) return;    
     *a = *b;
     copy(++a, ++b, b_size-1);
}


int main() 
{
int a[] = {1,2,3,4,5};
int *d = a;
int sum = 0;
for (int j = 0; j < 3; ++j)
sum += (a[j] * d[j + 1]) + (a[j + 1] * d[j]);
cout << sum;


int *b;
cout << "Copying array \n";
copy(b,a,5);//this does not work
//b = d;this works
cout << "Array copied \n";

for (int j = 0; j < 5; ++j)
cout << *(b+j) << " ";

system("pause");
return 0;
} 

[cire]

b is a pointer which points to... nothing. Dereferencing it results in undefined behavior, and that is what you are experiencing. You can't store something in some place that doesn't exist.

[abhishekm71]

As cire mentions, the pointer b is not pointing to anything. You need to allocate memory for the new array:

int *b = new int[5];

//
//
// and later don't forget to free the memory by calling delete.

delete [] b;

[MRKSalman0349]

thanks bro
can you plz tell me about shared_pointers in c++
actually i'm making a stack class and i made it using pointers and it works fine for me ...
but now i want to make this via shares_ptr to get rid of possible memory leaks
plzzzz guys help me .....

i m building the stack class by using linkedlist