1. I'm making a program with a default constructor and an overloaded constructor. They're both called by different rules and produces a testline of text when called. The assignment is to give the overloaded constructor default arguments to see what happens. I wonder, what is a default argument i an overloaded constructor?
Lets take class A such that
A default constructor is a constructor that doesn't take any arguments.
e.g.
A::A();
An overloaded constructor is a constructor that takes arguments.
e.g
A::A(int int_i, int int_j )
{
i = int_i;
j = int_j;
};
you can use the values of
int_i and
int_j to assign values for class A's member variables
i and
j.
If you write the overloaded constructor like this,
A::A(int int_i, int int_j = 0)
{
i = int_i;
j = int_j;
};
calling the constructor like
A a(2), will create an object
a with
a.i = 2 and
a.j = 0;
calling the constructor like
A a(2,9), will create an object
a with
a.i = 2 and
a.j = 9;
If you have a default constructor defined, don't make all the arguments of the overloaded constructor default arguments. That is because the compiler will not be able to tell the difference between the two constructors.
2. How do you instance an object from a class in different scope?
I think you are asking about something like this.
Class B is defined in Class A.So B is defined inside the scope of A. To create an instance of B, you should do something like this.
#include <iostream>
class A
{
public:
class B
{
public:
int i;
};
};
int main()
{
A::B b;
b.i = 9;
std::cout << b.i << std::endl;
} 3. How do you send an object "by value" to a function?
like this.
class A
{
...
}
int some_function_that_takes_an_object_of_class_A( A a )
{
.....
}
int main()
{
A a;
some_function_that_takes_an_object_of_class_A( a ); // sends a copy of a. the original a is not changed.
}
~sos~ has answered question 4.
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