Get and Set functions in C++ Query

Question

My teacher said that get and set functions are used in C++ as from them we can get value at runtime. Is it true? Aren't constructors used for this purpose to set value at runtime.

Answer 1

Constructors are used to generate the "default" values in an object.
Once created, however, "getters" and "setters" are simply methods that allow you to access private members of that object. They're named as such because one name their methods getValue() to get a private variable named value from an object or setValue(int) to set it.

It is often also convenient to do error-checking in these methods, and to call a selection of "setters" in the constructor to save on code or easily create multiple constructors.

Here is an example:

class MyClass
{
private:
    int value;
public:
    MyClass(int);

    void setValue(int);
    int getValue();
};

MyClass::MyClass(int _value)
{
    setValue(_value); // pass to "setter"
}

void MyClass::setValue(int _value)
{
    if (_value > 0) // error-checking here
        value = _value;
    else
        value = 0;
}

int MyClass::getValue()
{
    return value;
}