EECS 183 DISCUSSION 8 Hannah Westra Upcoming Due

EECS 183 DISCUSSION 8 Hannah Westra

Upcoming Due Dates ◦ Project 3 Due Tonight (10/28) at 6 pm ◦ Assignment 4 Due Next Friday (11/4) at 6 pm ◦ Final Project Options are Released ◦ Descriptions and Video Demonstrations ◦ Start thinking about groups

File Stream ◦ Up until now you’ve needed to #include <iostream>. Why? ◦ To be able to use the input stream cin and the output stream cout ◦ What is <fstream>, and why do we include it? ◦ If we want to use a file stream and read in data/input from a file, or write data (output) to a file

In pu >_chrysanthemum t u utp ts tre am USER INPUTS “chrysanthemum” am e r st o PROGRAM INPUTS “chrysanthemum”

Careful with input streams ◦ Do NOT use cin. eof() or my_ifstream. eof() as a condition ◦ Can sometimes cause undefined behavior ◦ INSTEAD: ◦ while (in. File >> x){…} // while reading into the file is still successful ◦ while (!in. File. fail()){…} //while reading into the file does not cause a fail state ◦ You can use cin. clear() or in. File. clear() or out. File. clear() to reset a fail state ◦ Where “out. File” is the variable name of your ostream ◦ A useful function to do this all was provided in lecture

Questions About Filestreams?

Bjarne Break!

Definition of a Class ◦ What is a class? ◦ A class is a container that can hold different types of objects (objects with different data types) ◦ A class is a user-defined data type ◦ Just like int and double and string are data types, so is the class you define ◦ A class is a way to group together related information

Thinking about Classes ◦ A class is like an object that holds multiple pieces of information ◦ You pass around a box that holds some more information inside it ◦ If you have access to the box, you also have access to what’s inside it

Let’s Create a Student Class ◦ What are some defining characteristics of a student? ◦ uniqname ◦ umid ◦ year ◦ A student has all of these attributes, so we could make a Student class, where these attributes are member variables ◦ This allows us to declare a Student (our custom data type) that holds attributes of the student as well

Student Class

Public vs Private ◦ A private member variable or member function means that only members of the class can access it ◦ Member variables are usually private, and we use setters and getters to access them ◦ A public member variable or function means that any part of the code can access that function or variable. Setters and getters are always public.

Is it a Constructor? ◦ There are 3 ways to tell ◦ 1) The function name is exactly the same as the class name ◦ 2) The function has no return type ◦ 3) The function starts with a capital letter (not definitive) ◦ How do we know which type of constructor it is? ◦ If it has no parameters (eg. Student()) then it is a default constructor ◦ If is has parameters then it is a non-default constructor

Declaring an object of type Student How would we declare and initialize this Student object? DEFAULT CONSTRUCTOR RUNS NONDEFAULT CONSTRUCTOR RUNS

Header Files vs Source Files ◦ Header files have the. h extension ◦ Header files are where class definitions and function declarations go ◦ Contains: ◦ Some member functions ◦ Including a print function ◦ Public and private members ◦ A default constructor ◦ A non-default constructor ◦ Getters ◦ Source files have the. cpp extension ◦ Source files are where function implementations go ◦ Has all the implementation of the declaration in the header file ◦ Be careful with syntax here!!! ◦ Scope Resolution Operator!

Example. h File

Example. cpp File

In main. cpp we want to… ◦ Make 3 instances of the class ◦ Call one with the default constructor ◦ Call the others with the non-default constructors ◦ Access elements and change them, probably using getters and setters ◦ Do something fun…

Upcoming Due Dates ◦ Project 3 Due Tonight (10/28) at 6 pm ◦ Assignment 4 Due Next Friday (11/4) at 6 pm ◦ Final Project Options are Released ◦ Descriptions and Video Demonstrations ◦ Start thinking about groups

Questions?