Intro to Computer Programming
Welcome to CSCI 1205

Chapter 1

Introduction to Computing and Programming

Topics

1.1 Introduction

1.2 Hardware and Software

1.3 How Computers Store Data

1.4 How a Program Works

1.5 Graphical User Interfaces

1.6 Objects

1.7 The Program Development Process

1.8 Getting Started with the Visual Studio Environment

1.1 Introduction

A program is a set of instructions that a computer follows to perform a task

Programs are commonly referred to as software

Without software, computers cannot do anything

Programmers, or software developers, create software

They are people with the training and skills necessary to design, create, and test programs

This book introduces fundamental programming concepts using C#

1.2 Hardware and Software

Hardware refers to all physical devices

A computer consists of many pieces of hardware that all work together

Each piece of hardware does its own work

A typical computer system contains:

The CPU

Main memory

Secondary storage devices

Input devices

Output devices

The CPU

The central processing unit is the part that actually runs programs

The most important part of a computer

Today CPUs are microprocessor

Commonly used CPU vendors are Intel and AMD

Main Memory

The computer’s work area

Where the computer loads instructions of programs and data for processing

Commonly known as RAM, random-access memory

Designed for CPUs to quickly access data stored at any random location in the RAM

They are a volatile type of memory

When the computer is powered off, the contents in RAM are erased

Secondary Storage Devices

Devices that can hold data for long periods of time, even when the power is off

Where important data and system files are stored

Most commonly used is the disk drive which stores data by magnetically encoding it onto a circular disk

Solid state drives have no moving parts, and operate faster than a traditional disk drive.

Optical devices such as DVD-ROMs and CD-ROMs are also popular

USB drives and SD memory cards  are small devices that plug into a port

Input Devices

Input is any data the computer collects from people and devices

Devices that collect the data and send them to the computer are called input devices

Commonly used input devices are touch screens, keyboards, mouses, scanners, microphones, and digital cameras

Output Devices

Output is any data the computer produces for people or devices

The device that generates output for a computer is called an output device

Commonly used output devices are screens, speakers, and printers

Software

Categorized mainly into system software and application software

System software are programs that control and manage the basic operations of a computer. Subcategories are:

Operating systems

Utility programs

Software development tools

Application software are programs that perform special tasks

1.3 How Computers Store Data

All data stored in a computer is converted to sequence of 0s and 1s; each sequence is called a bit

A computer’s memory is divided into tiny storage locations called bytes

Eight bits make a byte

Combinations of bits, 0s and 1s, are used to represent characters. For example,

The character ‘A’ is 65 in ASCII code, which is converted to binary format 1000001

When you press ‘A’, 1000001 will be stored in computer’s memory

Digital and Digital Data

“Digital” refers to anything that can only have two possible values

Digital data is the data that is stored in binary.

Digital devices are devices that work with binary data

Computers are digital devices

1.4 How a Program Works

CPU reads instructions written in machine language called instruction set

A program will be copied into memory for CPU to execute

CPU uses the “fetch-decode-execute” cycle for processing

Fetch: Reads instructions from memory

Decode: Decodes the instructions that were just read to determine how to perform operations

Execute: Actually performs the operations

Programming Languages

Machine languages: sequences of 0s and 1s

Assembly languages: use short words known as “mnemonics” to write program

Must be translated by assembler

Still considered low-level languages

High-level languages: more human readable languages that allow programmers to create programs without knowing how CPU works.

Modern languages are high-level

Keywords, Operators, and Syntax

High level languages use keywords that have special meaning and cannot be used for any purpose other than to write programs

Operators are keywords that represent special program functions such as addition, subtraction, and multiplication

Syntax is a set of rules that must be strictly followed to write computer-understandable instructions

Syntax error is a mistake or violation of these rules

Each instruction in a program is called a statement

Compilers and Interpreters

A compiler translates a high-level language program to a separate machine program for CPU to read and execute

Source code: the statements a programmer writes in a high-level language

Compilation: translates a text-based source code to binary codes

Interpreter reads, translates, and executes the instructions of a high-level language program

Examples are PHP, Perl, Python, and ASP.NET

1.5 Graphical User Interface

User interfaces allow users to interact with the computer. Categories are:

Command line interface (aka console interface)

Graphical user interface (GUI)- now the most commonly used

1.6 Objects

Most programming languages use object-oriented programming in which a program component is called an “object”

Program objects have properties (or fields) and methods

Properties – data stored in an object

Methods – the operations an object can perform

Controls

Objects that are visible in a program GUI are known as controls

Commonly used controls are Labels, Buttons, and TextBoxes

They enhance the functionality of your programs

There are invisible objects in a GUI such as Timers, and OpenFileDialog

The .NET Framework

The .NET Framework is a collection of classes and other codes that can be used to create programs for Windows operating system

C# is a language supported by the .NET Framework

Controls are defined by specialized classes provided by the .NET Framework

You can also write your own class to perform a special task

1.7 The Program Development Process

The process of creating a program is known as the programming development cycle

It has six phases:

Understand the program’s purpose

Design the GUI

Design the program’s logic

Write the code

Correct syntax errors

Test the program and correct logic errors

Algorithm, Pseudocode, Flowchart

An algorithm is a set of well-defined, logical steps that must be taken to perform a task

An algorithm that is written out in plain English is called pseudocode

A flowchart is a diagram that graphically depicts the steps of an algorithm

1.8 Getting Started with the Visual Studio Environment

Visual Studio 2015 is a professional integrated development environment (IDE)

You may install Visual Studio 2015 Community Edition (free programming environment available from download from Microsoft)

The Visual Studio Environment includes:

Designer Window

Solution Explorer Window

Properties Window

Auto Hide allows a window to display only as a tab of the edges

Menu Bar and Standard Toolbar

Menu bar provides menus such as File, Edit, View, Project, etc.

Standard toolbar contains buttons that execute frequently used commands

The Toolbox

Toolbox is a window for selecting controls to use in an application

Typically appears on the left side of Visual Studio environment

Usually in Auto Hide mode

The Toolbox

Toolbox is a window for selecting controls to use in an application

Divided into sections such as “All Windows Forms” and “Common Controls”

Tooltips

A Tooltip is a small box that pops up when you hover the mouse pointer over an item on the toolbar or toolbox.

Docked and Floating Windows

When a window such as Solution Explorer is docked, it is attached to one of the edges of the Visual Studio environment

When a window is floating, you can click and drag it around the screen

A window cannot float if it is in Auto Hide mode

Right click a window’s title bar and select Float or Dock to change between them

Projects and Solutions

Each Visual Studio application (including Visual C#) you will create is a project

A project contains several files.

Typically they are Form1.cs, Program.cs, etc.

A solution is a container that can hold one or more Visual Studio (including Visual C#) projects

Each project, however, is saved in its own solution

Specifying the Project Name

You can specify the project name the first time you save the project.

Displaying the Designer

Sometimes when you open an existing project, the project’s form will not be automatically displayed in the Designer

You should:

Right click Form1.cs in
the Solution Explorer

Click View Designer in
the pop-up menu