Lesson 1

Structure, union, enum

Is there object oriented world only?

Example: how to create a structure?


struct student
{
    int index;
    int semester;
};

Example: how to instantiate a structure?


int main()
{
    student s1, s2, s3;
    
    s1.index = 1;
    s1.semester = 3;

    s1.index = 2;
    s1.semester = 5;

    s1.index = 3;
    s1.semester = 7;
}

Example: how to create an enum?


enum person_type
{
    guest,
    student,
    lecturer,
    professor
};

Example: enum as a variable


int main()
{
    person_type somebody = guest;
    switch(somebody)
    {
        case student:
        case lecturer:
        case professor:
            std::cout << "Member of an university" << std::endl;
            break;
        case guest:
            std::cout << "Anybody" << std::endl;
            break;
    }
}

Task 2

Create student’s structure:

Add #include <string>
Create a structure of a student with field name (string)
Create two method headers before main function:
- student create();
- string to_string(student);
Modify main function:
- Create a new student via create method and assign value to a variable
- Display information about student using to_string.
Create definitions for:
- create – it reads all information from standard input (terminal)
- to_string – it returns a string build on all structure fields

Example: reading a string from standard input


int main()
{
    std::string text;
    std::getline(std::cin, text);
}

Example: how to work with union?


union X
{
    int   integer;
    float floating;
};

int main()
{
    X x;
    x.integer = 3;
    x.floating = 3.14f;
    std::cout << x.integer << std::endl;
    std::cout << x.floating << std::endl;
}