First thing which i wanted to implement are setters and getters. These functions are as names points for grabbing input data for classes and for giving output data from classes. Without these functions communication between classes would be difficult. Examples for setters and getters functions are below:

• setter

void setValue(double value)
{
    oldValue = value;
}

• getter

double getValue()
{
    return value;
}

Those are basic functions which i have lately implemented. Sometimes they can include other functionality like data check or more depend from needs.