Object-Oriented Programming using C++

Introduction

Anne DeFrance

CS 210

Class information on the web

• Syllabus includes:

– Text

– Grading criteria

– Final time

– Office hours

• Lecture schedule includes

– Reading assignments

– Schedule of lecture topics and exams

• Most of the lectures will be posted after class

– Link to assignments

What is expected in this course

– You come to class

• there will be quizzes which will be 15% of your grade.

– You read the material before you come to class

• There is required reading and reference reading.

– You ask questions in class if you need clarification

– You do your own programming.

– You keep your web page current.

The evolution of computers

• The first US computers were developed during WWII to plot artillery trajectories.

– In England, the first computer helped win the war by cracking the German code

• In the 50s and 60s, companies used mainframe computers costing millions of dollars, and big as a room

– Input was with punched cards, and only one job could run at a time

• By the 70s, minicomputers had been developed

– The PDP-11 Weiss talks about was a minicomputer

– 128 K of RAM

– The C compiler took 30 seconds to compile a 100 line program

– The C language was developed to run on this machine

The evolution of computer languages

• The first computers used machine language (zeros and ones)

– This was implemented by plugging and unplugging wires

• Assembly language was developed to avoid the zeros and ones

– There is a one-to-one correspondence between a machine instruction and an assembly language instruction

• High level languages: one instruction may contain several assembly language instructions

– FORTRAN and COBOL were early high level languages

– The C language was developed to write an operating system for a minicomputer (UNIX)

– Java and C++ are higher level languages than C

Evolution of C

• Unix proved to be a very popular operating system for several reasons

– It was portable between different platforms

– The source code was given to universities, and they modified (improved) the OS

• This led to a host of venders producing C compilers, adding their own features.

– In 1989 C was finally standardized (ANSI C)

• About this time Bjarne Stroustrup created C++ based on C, but object oriented

• C++ should be view as a completely new language, based largely on C.

From C to C++

• C++ was designed to be upward compatible with C

– A C program should compile on a C++ compiler

– If the C program uses any of the C++ new reserved words, it will not compile

– So, not too many reserved words were added to C++

• C++ has evolved. A new standard was established in 1999.

– At first, compilers had trouble implementing all the features of the new standard.

Philosophical differences between Java and C++

• C++’s main priority is getting correct programs to run as fast as possible

– Incorrect programs get no help from the compiler

– This means fewer compiler errors and more runtime errors

• Java’s main priority is not allowing incorrect programs to run.

– This means more compiler errors and fewer runtime errors.

Translating differences between Java and C++

• Java is compiled into bytecode, then interpreted into executable code.

– You do not get a file with the executable code.

– The .class file is the file containing the bytecode

– This makes the Java code portable.

• The C++ compiler generates executable code.

– This means that what you compile on one machine will not (usually) run on another machine.

Object-Oriented Programming using C++

Anne DeFrance

CS 210

Class information on the web

• Syllabus includes:

– Text

– Grading criteria

– Final time

– Office hours

• Lecture schedule includes

– Reading assignments

– Schedule of lecture topics and exams

• Most of the lectures will be posted after class

– Link to assignments

What is expected in this course

– You come to class

• there will be quizzes which will be 15% of your grade.

– You read the material before you come to class

• There is required reading and reference reading.

– You ask questions in class if you need clarification

– You do your own programming.

– You keep your web page current.

The evolution of computers

• The first US computers were developed during WWII to plot artillery trajectories.

– In England, the first computer helped win the war by cracking the German code

• In the 50s and 60s, companies used mainframe computers costing millions of dollars, and big as a room

– Input was with punched cards, and only one job could run at a time

• By the 70s, minicomputers had been developed

– The PDP-11 Weiss talks about was a minicomputer

– 128 K of RAM

– The C compiler took 30 seconds to compile a 100 line program

– The C language was developed to run on this machine

The evolution of computer languages

• The first computers used machine language (zeros and ones)

– This was implemented by plugging and unplugging wires

• Assembly language was developed to avoid the zeros and ones

– There is a one-to-one correspondence between a machine instruction and an assembly language instruction

• High level languages: one instruction may contain several assembly language instructions

– FORTRAN and COBOL were early high level languages

– The C language was developed to write an operating system for a minicomputer (UNIX)

– Java and C++ are higher level languages than C

Evolution of C

• Unix proved to be a very popular operating system for several reasons

– It was portable between different platforms

– The source code was given to universities, and they modified (improved) the OS

• This led to a host of venders producing C compilers, adding their own features.

– In 1989 C was finally standardized (ANSI C)

• About this time Bjarne Stroustrup created C++ based on C, but object oriented

• C++ should be view as a completely new language, based largely on C.

From C to C++

• C++ was designed to be upward compatible with C

– A C program should compile on a C++ compiler

– If the C program uses any of the C++ new reserved words, it will not compile

– So, not too many reserved words were added to C++

• C++ has evolved. A new standard was established in 1999.

– At first, compilers had trouble implementing all the features of the new standard.

Philosophical differences between Java and C++

• C++’s main priority is getting correct programs to run as fast as possible

– Incorrect programs get no help from the compiler

– This means fewer compiler errors and more runtime errors

• Java’s main priority is not allowing incorrect programs to run.

– This means more compiler errors and fewer runtime errors.

Translating differences between Java and C++

• Java is compiled into bytecode, then interpreted into executable code.

– You do not get a file with the executable code.

– The .class file is the file containing the bytecode

– This makes the Java code portable.

• The C++ compiler generates executable code.

– This means that what you compile on one machine will not (usually) run on another machine.

Some reasons to use C++

• C++ is widely used in industry

• Generic code is fast and relatively easy

• C++ allows operator overloading

• The Standard Template Library is very powerful