Table of Contents
- 1 What is std :: initializer_list?
- 2 What is the difference between copy list initialization and direct list initialization?
- 3 Why initialization list is used in C++?
- 4 What is uniform initialization in C++?
- 5 What are aggregates in C++?
- 6 What is an aggregate class C++?
- 7 Should we initialize every member variable in the initializer list?
- 8 Should I use std::initializer_list?
What is std :: initializer_list?
An object of type std::initializer_list is a lightweight proxy object that provides access to an array of objects of type const T . a braced-init-list is used to list-initialize an object, where the corresponding constructor accepts an std::initializer_list parameter.
What is the difference between copy list initialization and direct list initialization?
Why does the standard differentiate between direct-list-initialization and copy-list-initialization? We know that T v(x); is called direct-initialization, while T v = x; is called copy-initialization, meaning that it will construct a temporary T from x that will get copied / moved into v (which is most likely elided).
What is an aggregate constructor C++?
Formal definition from the C++ standard (C++03 8.5. 1 §1): An aggregate is an array or a class (clause 9) with no user-declared constructors (12.1), no private or protected non-static data members (clause 11), no base classes (clause 10), and no virtual functions (10.3).
What is the difference between member variable initialization and assignment in a constructor?
What is the difference between initialization and assignment? Initialization gives a variable an initial value at the point when it is created. Assignment gives a variable a value at some point after the variable is created.
Why initialization list is used in C++?
The initializer list is used to directly initialize data members of a class. An initializer list starts after the constructor name and its parameters.
What is uniform initialization in C++?
Uniform initialization is a feature in C++ 11 that allows the usage of a consistent syntax to initialize variables and objects ranging from primitive type to aggregates. In other words, it introduces brace-initialization that uses braces ({}) to enclose initializer values.
What is direct initialization?
Direct Initialization or Assignment Operator (Syntax) This assigns the value of one object to another object both of which are already exists. Copy initialization is used when a new object is created with some existing object. This is used when we want to assign existing object to new object.
What is direct initialization in C++?
Direct initialization applies when initializing objects without explicit assignment. It also is also used for explicit casts, whether function-style or via static_cast and applies to Lambda closure arguments captured by value (which may be regarded as a special case of member initialization).
What are aggregates in C++?
In C++, aggregation is a process in which one class defines another class as any entity reference. It is another way to reuse the class. It is a form of association that represents HAS-A relationship.
What is an aggregate class C++?
You may also run across the term aggregate class in your C++ journeys, which is defined as a struct or class that has no provided constructors, destructors, or overloaded assignment, has all public members, and does not use inheritance — essentially a plain-old-data struct.
What is the difference between variable declaration and initialization?
Declaration of a variable in a computer programming language is a statement used to specify the variable name and its data type. Declaration tells the compiler about the existence of an entity in the program and its location. Initialization is the process of assigning a value to the Variable.
What is the difference between declaration and initialization of an array?
Array declaration tells the compiler about the size and data type of the array so that the compiler can reserve the required memory for the array. Array Initialisation assigns values to the array elements i.e. it stores values in the memory reserved for the array elements.
Should we initialize every member variable in the initializer list?
We should strive to initialize every member variable in the initializer list, because if we don’t plain old data types remain uninitialized and contain garbage values, not even zeroes. The problem is, that in C++03, aggregates can not be initialized in the initialization list but instead need to get their values assigned later.
Should I use std::initializer_list?
`std::initializer_list` should be treated carefully. If you write a class that can really benefit from it, use it, but be aware of the interference with normal constructors. In addition, avoid using `std::initializer_list`s as standalone objects. There is not much use to it, and there are some problems with auto type deduction.
What is aggregate initialization in C++11?
Until C++11, aggregate initialization could only be used in variable definition, and could not be used in a constructor initializer list, a new-expression, or temporary object creation due to syntax restrictions.
How is an array element initialized in C++?
Each direct public base, (since C++17) array element, or non-static class member, in order of array subscript/appearance in the class definition, is copy-initialized from the corresponding clause of the initializer list.