Update STACK_USING_ARRAY.cpp

[arjunjain8887]

1. Memory Management: Ensured proper deallocation of memory using delete[] for arrays.
2. Error Handling: Added checks for invalid capacities and empty stack conditions.
3. Corrected Logic: Fixed the condition in isfull() and improved overall logic flow.
4. User Feedback: Enhanced user feedback messages to make it clearer what went wrong.
5. Code Readability: Improved indentation and spacing for better readability.
6. Consistent Return Types: Ensured that functions like peek() return a consistent value even in error cases.

[pravocodes]

There are conflicts with the main branch please resolve those to get merged.

[harshangvirani]

@pravocodes please assignee this task to me

[pravocodes]

Yes I have assigned @harshangvirani