Remember that derived classes can access the public and protected members of their base class, but none of the private members. If the member variable in the base class is protected (rather than private), then the derived class can assign it directly. However, this is bad style in OOP as it undermines data-hiding. A protected mutator (set accessor) would be a better option.
We use the class constructor initialiser list to transfer values to the base class constructor.
Consider the following class definitions:
class A {
private:
int m_x;
int m_y;
public:
A (int, int);
// ...
};
class B : public A {
B (int, int);
// ...
};
Class A has two data members. Being built-in types, we must initialise those members during construction otherwise they'd be left in an uninitialised state. We could initialise them via the constructor body:
A::A (int x, int y) {
m_x = x;
m_y = y;
}
However, this is inefficient because both m_x and m_y must exist before we enter the constructor body, so we are actually instantiating both variables first and then initialising them via assignment. Although this costs very little when initialising built-in types, for more complex types initialisation through assignment can add an unacceptable overhead.
It is always more efficient to initialise variables (including member data) at the point of instantiation as soon as we have a value to assign to them. We achieve that in class constructors by using an initialiser list:
A::A (int x, int y): m_x {x}, m_y {y} {}
The constructor initialiser list begins with a colon (:) and is followed by a comma-separated list of initialisers, followed by the (now empty) constructor body. Initialiser lists can also be used to initialise base classes, thus the B class constructor can be implemented in the same way, as follows:
B::B (int x, int y): A {x, y} {}
Note how the initialiser, A {x, y}, invokes the public base class constructor A::A (int, int).
Default initial value of extern integral type variable is zero otherwise null.
Everything is an object, and "typed" based on assignation. Your variable will be given a class when you declare it to be something, and the class will depend on what value you give the variable. It is always an object though, and its class may change if you change its value.
A variable declared as final can't be modified, once a value is assigned.
Register storage class is a compiler hint that the variable will be often used, and that it should generate code, if it can, to keep the variable's value in a register.
Default values are available for any class or instance variable. If you do not specify a value for a class or instance variable the JVM will provide a default value that will ensure that the system does not end up with any unexpected errors because you used a variable that was not initialized. Ex: Public class Test { int I; } In the above class we have just declared an instance variable called 'I' but we haven't associated any value to it. The JVM automatically assigns 0 as the default value to this variable.
Default initial value of extern integral type variable is zero otherwise null.
A private variable is one that is accessible only to the current class and cannot be accessed by any other class, including the ones that extend from it. A final variable is one that cannot be modified once it is initialized and assigned a value.
Variable
Just type declare then the variable that you desire to assigned a certain constant value on it. Just type declare then the variable that you desire to assigned a certain constant value on it.
3x+2 x is a variable. A variable is a symbol (x, y, etc...) that does not have an assigned value.
The definition of constant variable is a variable whose value cannot be changed once it has been assigned a value for an experiment. It is the variable held steady, or constant, for a specific experiment.
A constant.
None. A letter has no numerical value unless it represents a variable and a value is assigned to it.
Everything is an object, and "typed" based on assignation. Your variable will be given a class when you declare it to be something, and the class will depend on what value you give the variable. It is always an object though, and its class may change if you change its value.
And what is the question? - The value of such an expression will depend on the value assigned to the variable, in this case, "t".
A variable declared as final can't be modified, once a value is assigned.
Register storage class is a compiler hint that the variable will be often used, and that it should generate code, if it can, to keep the variable's value in a register.