Welcome to COMP 1001First Year Computer Science

Lecturer: Fintan Costello

Where you are

COMP 1001:

Introduction to Programming (Tues@10/Thurs@12; Fintan)

Information Technology (Wed@12; Joe Carthy)

This class includes:

Science students Computer Science Denominated Entry students BA Computer Science students Actuarial & Financial students

Resources for the programming course

Textbook: Introduction to JAVA Programming, Y. Daniel Liang. Prentice Hall, 4th ed. Campus bookstore.

We’ll be using this textbook a lot: you should get it. Make sure you get the 4th edition!

Web site: http://inismor.ucd.ie/~fintanc/cs1001Look here to find these slides, course rules and instructions, exam info, practicals, and so on.

Owen Fallon (owen.fallon@ucd.ie; extn 2917) is your student advisor: he’s there to help with any problems…

What will you learn on this course?

How to make a computer do what you want:•Write programs to quickly solve complex problems

You will also develop a useful attitude towards computers•Not to be afraid when things go wrong, but to debug

•Write programs to process information in various ways

•Write programs to respond to different situations.

•To try things on your computer and learn from your mistakes

•To solve problems in a clear, unambiguous and precise way.

Why would you want to learn this?

Everyone should be able to do some programming (it’s the 21st century version of being able to type)

Being able to program allows you to create useful tools in any area of study

Psychology:Computational theory of mind is dominant in psychology today

Languages: Programming is closely related to linguistics Using and programming automated translation aids is part of the work of a professional translator

Why learn programming? More reasons

Physics: Computational simulation

Genetics: Computational analysis of gene structure

Large-scale experiments run by computer

Business: Runs on computer program infrastructure

genome projects run by computer

Programs to predict market performance, test implications of economic changes

There is no area where a knowledge of programming is not a noticable advantage

Ireland needs programmers!

From Fourth Report of the Expert Group on Future Skills Needs presented to the Tánaiste and Minister for Enterprise, Trade and Employment and Minister for Education and Science, October 2003.

Year Demand for New Computer Graduates

Number of New Computer Graduates

Gap

2006 2,807 1,866 -9412007 3,094 1,583 -

1,5112008 3,417 1,563 -

1,8542009 3,777 1,535 -

2,242

COMP 1001 intro to programming: what you do

Attend programming lectures twice weekly

Attend practicals once weekly (1 * 2 hours)

Textbook is required reading

Marks based on practical work, plus2 Exams (Christmas: MCQ exam,

Summer: Full written exam)

Attend architecture lectures once weekly

COMP 1001: Grading details

Practical work must be done correctly and submitted (25%)

Christmas Programming & IT multiple choice exam (15%)

Summer Programming & IT full written exam (60%)

Practical work must be satisfactory to pass COMP 1001

Programs and algorithms: some terms

A program is a series of instructions or commands to a computer

Running a program == carrying out the instructions

A well written program implements an algorithm which solves a problem

An algorithm is a precise description of how to solve a problem

Algorithm for making tea

boil water;put teabag into cup;pour water into cup until full;wait 3 minutes;remove teabag;if (want milk){ put milk into cup; }if (want sugar){ put sugar into cup; }stir;

Algorithms

An ALGORITHM is:

1. Unambiguous

2. Executable

3. Terminating

Problem: open a door

Algorithm:

read sign on door;if (sign says "pull") { pull the door open;} else { push the door open;}

Will this work for all doors?

Problem: Say hello to someone

Algorithm:

Ask the person’s name;Remember their name:

NAME their name; Say(“Hello “ + NAME);

Programming languages

Natural languages: French, English, Swahili…

Programming languages: C, perl, Java...

Natural languages are forgiving: if you have wrong the grammar, pronounciation, or speling, people can still understanding you be.

Computers are not as smart as people: if you don’t have your program’s grammar and spelling exactly right, the computer will not understand and will give an error

Your first java programWelcome.java (L, p. 15)

// Welcome.java: this application prints// a welcome message

public class Welcome{ public static void main(String[] args) { System.out.println("Welcome to Java"); }}

Reseved words

// Welcome.java: this program prints// a welcome message

public class Welcome{ public static void main(String[] args) { System.out.println("Welcome to Java"); }}

The words in bold are reserved words: they mean something special in the java programming language.

Reserved words are case-sensitive: Public is wrong.

What do these words mean?

// Welcome.java: this program prints// a welcome messagepublic class Welcome{ public static void main(String[] args) { System.out.println("Welcome to Java"); }}

class is a word that identifies something as a program in java

public is a modifier which identifies something as publicly accessible (other programs can “call” it, which means run it)

main identifies the main part of a program (the bit that does most of the work). We’ll explain static and void later.

Blocks {......}

A block is a sequence of code between matching curly brackets

This block identifies everything that is in the public class Welcome

This block identifies everything that is in the main part of the class.

// Welcome.java: this program prints// a welcome messagepublic class Welcome{ public static void main(String[] args) { System.out.println("Welcome to Java"); }}

Statements

A statement is an action.

A statement ends with a semi-colon ;

System.out.println("Welcome...");

println means ‘print this on a line of its own’ (you can also use print, which doesn’t start a new line).

System.out means that println is an action carried out by the output part of a set of Java programs which you can use to interact with your computer’s System.

We’ll learn more about this later when we talk about methods

Comments in Java

Comments are simply notes for the programmer to remind themseleves and other programmers what a program is meant to do. Comments can contain any text you like

// this is a one line comment// and here is another

/* this comment can extend over several lines ....... */

Comments are not java commands. Always comment your programs! It helps you remember what’s going on.