No default constructor, When there is [duplicate] - c++

Question

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no default constructor exists for class
(5 answers)
Closed 1 year ago.
Why do I get the error "No default constructor exists for class "Sub", even though I have the constructor for Sub class"
class Base{
private:
int x;
public:
Base(int number)
{
x = number;
}
virtual void print(void) = 0;
};
class Sub: public Base{
public:
Sub(int x): Base(x) {
}
void print()
{
cout << "Testing" << endl;
}
};

Answer 1

A default constructor is one taking NO arguments. A default constructor is one which requires no provided arguments.
Base() and Base(args = default) are both considered default constructors, as no arguments are required. Please note the second one is Pseudo Code.
class Base{
private:
int x;
public:
Base(int number)
{
x = number;
}
virtual void print(void) = 0;
};
class Sub: public Base{
public:
Sub(int x): Base(x) {
}
void print()
{
cout << "Testing" << endl;
}
};
Your code definitely does not have a default constructor.
Declaring a constructor automatically disables the compiler-created default contructor.
More info:
https://en.cppreference.com/w/cpp/language/default_constructor
https://www.geeksforgeeks.org/constructors-c/
https://www.ibm.com/docs/en/zos/2.2.0?topic=only-default-constructors-c
https://www.w3schools.com/cpp/cpp_constructors.asp
https://learn.microsoft.com/en-us/cpp/cpp/constructors-cpp
https://www.learncpp.com/cpp-tutorial/constructors/