CS 101 Computer Programming and Utilization

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1 CS 101 Computer Programming and Utilization Lecture 14 Functions, Procedures and Classes. primitive and objects. Files. Mar 4, 2011 Prof. R K Joshi Computer Science and Engineering IIT Bombay rkj@cse.iitb.ac.in

2 Revision global s: s can share s member s usual input parameters but they can be accessed by any usual return value + sharing of private s class: set of member s + set of private s + constructor (+ destructor: we will talk about it later) dot operator: for invocation of member s a return value can be assigned as usual object: instance of a class class is like a type and object is like a value private vs. public many instance of a class can be created of private s define the state of an object at a given point of time

invocation of member s a return value can be assigned as usual object: instance of a class class is like a type and object is like

3 The model of s: body vs. invocation input parameters body: definitions local s, accesses to input parameters computing a return value invocation local s return Values

4 While pure s do not use history, procedures may use global input parameters procedure body: definitions local s, accesses to input parameters computing a return value invocation local s return Values

5 Inovcation can access the global procedure body: definitions local s, accesses to input parameters computing a return value global input parameters procedure invocation local s global return Values

computing a return value global input parameters

6 Multiple invocations: separate copy of local s, but a shared copy of globals procedure body: definitions local s, accesses to input parameters computing a return value global input parameters input parameters procedure procedureinvocation invocation local s local s global return Values

parameters computing a return value global input parameters input

7 Classes private s

8 Classes member s

9 Classes sharing of private s by member s

10 Classes constructor constructor

11 Classes constructor initializes private s constructor

12 Objects: Instances of classes Object 2 Object 3 Object 1 constructor

13 Objects: Each one keeps a separate copy of the set of private s Object 3 Object 2 Object 1 constructor

14 Objects: The dot operator to invoke member s on objects (also called sending messages to objects) Object 3 Object 2 Object 1 constructor Invoke a member Supplying input parameters

15 Objects: a result comes out of member invocation Object 3 Object 2 Object 1 constructor Out comes the return result Invoke a member Supplying input parameters

16 The object's state (private s) may get modified during member invocation Object 3 Object 2 Object 1 constructor Out comes the return result Invoke a member Supplying input parameters

17 Libraries of classes A pre implemented collections of classes Used for reusability Separately compiled and kept somewhere in the system The programmer includes the declarations The pre compiled libraries are linked before the executable file gets produced Recall separate compilation

programmer includes the declarations The pre compiled libraries are

18 Files A file is a unit of storage on disk You have different kinds of files on your disk Text files, documents Pictures, photographs Music Source code Executable files Lab handouts

19 Creating and accessing our own files through C++ You have so far used editors or copy commands to create your own files You can also create them from a program Or.. existing files can be accessed and modified from a program Scientific, data oriented computations Programs have computations Data comes in from files or goes out into files

. existing files can be accessed and modified from a program Scientific, data

20 File handling library Include <fstream> For input and output on files Classes For performing output on files For input from files For doing both both Class ofstream Class ifstream Class fstream

21 Some s of files open() opening a file is_open() checking if it's open eof() end of file reached? close() closing a file operator << for output to file operator >> input from file

Appendix K Introduction to Microsoft Visual C++ 6.0

Appendix K Introduction to Microsoft Visual C++ 6.0 This appendix serves as a quick reference for performing the following operations using the Microsoft Visual C++ integrated development environment (IDE):