If the user’s goal was to create an object in some memory location, then new seemed like a natural approach since forwarding references, variadic templates and placement new were not a thing back in those days. As correctly pointed out by @T.C. templates were released in 1990 and placement new in 1989. Variadic templates on … Read more
With the following line you are not creating a new String object in the heap but reusing a string literal (if already available): String message = “Hai”; “Hai” is a string literal in the string literal pool. Since, strings are immutable, they are reusable so they are pooled in the string literal pool by the … Read more
Opens a new window with the url you supplied 🙂 <button class=”button” onClick=”window.open(‘http://www.example.com’);”> <span class=”icon”>Open</span> </button>
I’m out for a compelling reason. It depends on how you define “compelling”. Many of the arguments you have thus far rejected are certainly compelling to most C++ programmers, as your suggestion is not the standard way to allocate naked arrays in C++. The simple fact is this: yes, you absolutely can do things the … Read more
Ugh, my sympathy. This is going to depend a lot on your compiler, your libc, etc. Some rubber-meets-road strategies that have “worked” to varying degrees for us in the past (/me braces for downvotes) are: The operator new / operator delete overloads you suggested — although note that some compilers are picky about not having … Read more
Just do: MyClass::MyClass(int m_size) : size(m_size), vec(m_size, 0) You already seem to know about initializer lists, why not initialize vector there directly? vec = new vector<int>(size,0); is illegal because new returns a pointer and in your case vec is an object. Your second option: vector<int> temp(size,0); vec = temp; although it compiles, does extra work … Read more
There’s no new/delete expression in C. The closest equivalent are the malloc and free functions, if you ignore the constructors/destructors and type safety. #include <stdlib.h> int* p = malloc(sizeof(*p)); // int* p = new int; … free(p); // delete p; int* a = malloc(12*sizeof(*a)); // int* a = new int[12]; … free(a); // delete[] a;
In the new Standard for C++ (C++11), you can do this: int* a = new int[10] { 1,2,3,4,5,6,7,8,9,10 }; It’s called an initializer list. But in previous versions of the standard that was not possible. The relevant online reference with further details (and very hard to read) is here. I also tried it using GCC … Read more
The new operator creates a new object of a type that’s known statically (at compile-time) and can call any constructor on the object you’re trying to create. It’s the preferred way of creating an object – it’s fast and the JVM does lots of aggressive optimizations on it. Class.forName().newInstance() is a dynamic construct that looks … Read more
If T doesn’t have trivial destructor, then for usual compiler implementations, new T[1] has an overhead compared to new T. The array version will allocate a little bit larger memory area, to store the number of elements, so at delete[], it knows how many destructors must be called. So, it has an overhead: a little … Read more