Dynamic Data Structures II Lecture Notes PDF

22. Dynamic Data Structures II 579 Recap: vector Can be initialised with arbitrary size n Supports various operations: e = v [ i ]; // Get element v[i] = e; // Set element l = v. size (); // Get size v. push_back ( e );...

22. Dynamic Data Structures II 579 Recap: vector Can be initialised with arbitrary size n Supports various operations: e = v [ i ]; // Get element v[i] = e; // Set element l = v. size (); // Get size v. push_back ( e ); // Append element... A vector is a dynamic data structure, whose size may change at runtime 580 Our Own Vector! We’ll implement our own vector: our_vector 581 Vectors in Memory Already known: A vector has a contiguous memory layout Question: How to allocate a chunk of memory of arbitrary size during runtime, i.e. dynamically? 582 new for Arrays underlying type new T[expr] new-Operator positive integer value, value n Effect: new contiguous chunk of memory n elements of type T is allocated This chunk of memory is called an array (of length n) 583 new for Arrays underlying type p = new T[expr] new-Operator positive integer value, value n Value: the starting address of the memory chunk p Type: A pointer T * 584 Pointer Arithmetic: Pointer plus int T * p = new T [n]; // p points to first array element p p+3 p+n Question: How to point to rear elements? → via Pointer arithmetic: p yields the address of the first array element, *p its value *(p + i) yields the value of the ith array element, for 0 ≤ i < n *p is equivalent to *(p + 0) 585 Pointer Arithmetic: Pointer plus int int* p0 = new int{1,2,3,4,5,6,7}; // p0 points to 1st element int* p3 = p0 + 3; // p3 points to 4th element *(p3 + 2) = 600; // set value of 6th element to 600 std::cout