Why it's showing errors

Question

Please can anyone explain to me the logic behind the code that i have mentioned below.

In the below code it's not showing errors if i include the lines =====> :B(i) on class C and :A(i) on class B constructors. Why it's not showing errors after i included these lines on the code kindly explain to me any of you guys.

https://code.sololearn.com/cToqBELWKjah/?ref=app

Answer 1

All of the constructors for A, B and C in this code require an input parameter (i). When you instantiate C in main, automatically it must also instantiate its superclass - B. The B constructor needs an argument to pass into its parameter i. So the syntax, C(int i): B(i) {, tells the compiler to pass i as the argument to construct B.

In turn, B automatically must call its superclass constructor A and pass an argument. The syntax, B(int i): A(i), passes i as the argument for A's constructor.

The code would work without adding the extra syntax if A and B both were given another constructor that requires no argument.

A() {
cout<<"just plain A()"<<endl;
}

And

B() {
cout<<"just plain B()"<<endl;
}