There is currently no way to do this without rolling your own make_array, there is a proposal for this N3824: make_array which has the following scope: LWG 851 intended to provide a replacement syntax to array<T, N> a = { E1, E2, … }; , so the following auto a = make_array(42u, 3.14); is well-formed … Read more
In C++, an object is considered fully initialised when execution enters the body of the constructor. You said: “i wanted to know why const must be intialized in constructor initializer list rather than in it’s body ?.” What you are missing is that initialisation happens in the initialisation list, and assignment happens in the body … Read more
Edit: you should now use brew services start mongodb, as in Gergo’s answer… When you install/upgrade mongodb, brew will tell you what to do: To have launchd start mongodb at login: ln -sfv /usr/local/opt/mongodb/*.plist ~/Library/LaunchAgents Then to load mongodb now: launchctl load ~/Library/LaunchAgents/homebrew.mxcl.mongodb.plist Or, if you don’t want/need launchctl, you can just run: mongod It … Read more
You can’t use statements in the middle of your class. It have to be either in a block or in the same line as your declaration. The usual ways to do what you want are those : The initialization during the declaration public class MyClass{ private int i = 0; } Usually it’s a good … Read more
The default value of int is 0 and that is the value it will have in both JavaSE and JavaEE unless it was assigned with another value. You can’t have an uninitialized int class member in Java (or any other primitive). In your example you show the int is a class member, in the other … Read more
Here is what I think: because b is not final, the compiler is free to reorder the operations as it likes, right? So this, fundamentally is a reordering issue and as a result a unsafe publication issue Marking the variable as final will fix the problem. More or less, it is the same example as … Read more
For S, they have the same effect. Both invoke the constructor S::S(int) to initialize the objects. S s2{12}; is regared as list initialization (since C++11); S is not an aggregate type and not std::initializer_list, and has no constructor taking std::initializer_list, then If the previous stage does not produce a match, all constructors of T participate … Read more
Yes, the order of construction is always guaranteed. It is not, however, guaranteed to be the same as the order in which the objects appear in the initializer list. Member variables are constructed in the order in which they are declared in the body of the class. For example: struct A { }; struct B … Read more
From suns java tutorial It’s not always necessary to assign a value when a field is declared. Fields that are declared but not initialized will be set to a reasonable default by the compiler. Generally speaking, this default will be zero or null, depending on the data type. Relying on such default values, however, is … Read more
Singleton singleton = Singleton.getInstance(); is the correct way. Make sure your getInstance() method is indeed static. Since your Singleton implementation is far from being safe – your object can be instantiated via reflection, you may want to create a singleton based on enum