How to Initialize Data Members in C++ From C++11 untill C++20.png

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cpp20

Throughout this course, you will learn all the options to initialize data members in C++ using a simpler syntax and safer code. More specifically, in this mini course you will learn non-static data member initialization, inline variables, designated initializers, and more. Additionally, you’ll see the changes and new techniques from C++11 to C++20 to really round out your understanding.

Initializing Data Members: From C++11 till C++20

# Copy constructor

The compiler initializes the fields in all the constructors, including the copy and move constructors. However, when a copy or move constructor is the default, there's no need to perform that extra initialization.

Now, let’s update our previous examples with copy constructors:

#include <iostream>
#include <string>

int initA() {
    std::cout << "initA() called\n";
    return 1;
}

std::string initB() {
    std::cout << "initB() called\n";
    return "World";
}

struct SimpleType {        
    int a { initA() }; 
    std::string b { initB() };

    SimpleType() { }
    SimpleType(std::string s) : b(std::move(s)) { }
    
    SimpleType(const SimpleType& other) {
        std::cout << "copy ctor\n";
        
        a = other.a;
        b = other.b;
    };

};

int main() {
    SimpleType t1;
    std::cout << "SimpleType t2 = t1:\n";
    SimpleType t2 = t1;
}

In this lesson, you will learn how non-static data member initialization works with move and copy constructors.

__default

NSDMI: Copy and Move Constructors

Copy constructor