How to copy one array to the end of another array?

Urgent! Thank you very much.

First you get the length of both Arrays: short int thing[] = {1,2,3,4};
int length = sizeof thing / sizeof (short);
And then if had both lengths add both to one: lenght += length2;
And then create a new Array: int *array = new int [length];
And then copy both arrays into the one and to not forget to delete the both arrays
for (int i =0; i<=length; i++)
{ array[i]=thing[i];} and delete thing.

The best method could be to use memcpy


int i[10];
int j[10];
memcpy( &i[10], j, sizeof(int)*10 );