Objectives

Notes

• Dynamic memory is memory that is allocated at run time off of the heap.
• type * var{nullptr} declares a pointer to a type and initializes it to nullptr.
• nullptr , NULL or 0 are all pointers to nothing
• When you declare a pointer, it should be initialized to null or a valid pointer.
• To allocate memory:
  • type * new type;
  • type * new type[const int expression]
• If you allocate memory, you must deallocate it when you are finished
  • delete pointerVar;
  • delete[] pointerVar;
• Memory allocated with new[] must be deleted with delete[]

• int * ary{new int[size]};
  ...
  
  delete [] ary;
     

• You must always perform pointer operations on valid pointers, not nullptr.
• Typical code

  • 
    int * ary{nullptr}
    
    ...
    ary = new int [newSize];
    
    ...
    if (ary != nullptr) {
        // some operation on the array.
    }
    
    ...
    
    if (array != nullptr) {
        delete[] ary;
    } 

• Some common errors
  • Allocating dynamic memory without deleting it creates a memory leak, and can cause your program to crash.
  • Freeing a pointer that has been freed will cause an error.
  • Freeing nullptr can cause memory errors
  • Pointing to memory that has been freed is a dangling pointer.
    • This can cause memory leaks or memory corruption.
• type function (type *& var) to pass by reference.