Fundamentals of Programming Lecture 1 Agenda

Fundamentals of Programming

• Lecture 1

Agenda

• What the module is all about.
• Assessment.
• What is programming?
• What is hardware, an operating system, software?
• What is a computer language?

What the module is all about.

• By the end of the module you should be able to write reasonably sized VB.NET programs
• You should have a solid basis of how programming works (Principles)
• The latter will allow you to explore VB.NET yourself in greater details, or EVEN to learn a new language independently!

About The Module

• Assignments
• Practical tests (computer-lab)
• Test I – general programming problems
• Test II – db access
• Tutor
• Vasiliy Kuznetsov
• Senior Lecturer
• Westminster International University in Tashkent

What is a Computer?

• Computers can handle repetitive chores without becoming bored or exhausted.
• A computer is programmable to handle different tasks:
• Financial calculations
• Processing words
• Playing games
• Computer actions are composed of huge numbers of extremely primitive operations
• The computer gives the illusion of smooth interaction because it executes these operations with a great speed.
• Computers are flexible: they can handle a wide range of tasks.

What is Programming?

• A program tells the computer the sequence of steps needed to fulfill a task.
• A programmer designs and implements these programs.
• Most computer users are not computer programmers.
• Programming is an essential skill for a computer scientist.

What is a Computer Language?

• A special language that allows people to communicate with computers
• Modern computer languages use words from human languages, have rules of grammar, syntax and punctuation
• In general, programming language is a way to say to a computer what to do

The Anatomy of a Computer (CPU, Memory, and bus)

• CPU (Central Processing Unit):
• Plastic, metal and mostly silicon.
• Composed of several million transistors.
• Enormously complicated wiring.
• Performs program control, arithmetic, and data movement.
• Locates and executes program instructions.
• Memory:
• RAM (Random Access Memory): read-write memory.
• ROM (Read Only Memory): contains certain programs that must always be present.
• Secondary storage
• (e.g. a hard drive) provides persistent storage.
• Bus
• is a set of electrical lines that connect the CPU, RAM, and other devices.

The Anatomy of a Computer

Programming languages: 1st Generation

• Machine instructions:
• Extremely primitive
• Encoded as numbers:
• 161 40000 45 100 127 11280
• Tedious and error prone to look up numeric codes and enter them manually.
• Each processor has its own set of machine instructions.

Programming languages: 2nd Generation

• Assembler
• One-to-one correspondence with instructions
• Assigns short names to commands:
• mov 40000, %eax
• sub 100, %eax
• Makes reading easier for humans
• Translated into machine instructions by another program
• Still processor dependent

Programming languages: 3rd Generation

• Higher-level languages:
• Independent of the underlying hardware
• Easiest for humans to read and write
• if (int_rate > 100)
• MessageBox("Interest rate error");
• Translated by compilers into machine instructions

Programming languages: 4th Generation

• Indicates “What to do” rather then “How to do that”
• Select * From tb_users
• SQL, Report generators

Compiled languages vs. Interpreted

• Compiler converts source code into machine-specific instructions BEFORE execution (at compile time)
• Faster execution
• Need to recompile to make changes
• C++, .Net, Java
• Interpreter converts source code into processor-specific instructions DURING the execution (run-time, just-in-time)
• Slower execution
• Allows to change code at run-time
• PHP, JavaScript

• The Compilation Process (Diagram)

The Compilation Process (Definitions)

• You write source code - that is your program
• The compiler is a program that translate your source code into object code
• Object code consists of machine instructions and information on how to load the program into memory
• A linker program takes the object code from your program and the code from the various libraries and builds them into an executable file
• Libraries contain the (already translated) code used by your program (such as System.Data)

The need to abstract the operating system

• Platform dependency
• Solution – another abstraction layer
• Java VM, .NET Framework (Mono project)

.Net Compilation (schematic)

• Run Time

• Source Code

• Microsoft Intermediate Language

• CLR just in-time compiler

• Native code

• The End