in C$++$ Write a loop that sets each array element to the sum of itself and the next element, except for the last element which stays the same. Be careful not to index beyond the last element. Ex: The first element is $30$ or $\backslash (10+20\backslash ),$ the second element is $50$ or $\backslash (20+30\backslash ),$ and the third element is $70$ or $\backslash (30+40\backslash ).$ The last element remains the same.