Introduction to Computer Programming (general background)

Introduction to Programming
授課老師: Chao-Lung Yang (楊朝龍)

Why do we need to learn
programming?
 When did you have your first computer?
 Did you learn programming or coding before?
 How is this world running under computing?
 Let’s look at how other people thinking?
 What most school don't teach

Introduction
 Basis of Programming Language
 Introduction of C#

Computer Program
 What is a computer program?
 Series of instructions that directs computer to perform
tasks
 Simply, a program is like a converter, which reads an
input and outputs useful information

Windows Applications
 Windows Applications
 A Graphical User Interface (GUI)
 Allows you to interact with the software using text, graphics,
and visual images such as icons
 Controls how you enter data and instructions and how the
screen displays information
 Console Applications
 For DOS or UNIX/Linux
 Designed to be used by a text-only computer interface
(Command-line Interface)
 Interacts with a console application using only a keyboard

Types of Programming Languages
 Programming language: a notion for writing programs and
is used to communicate instructions.
 Programming languages can be divided into low-level
languages and high-level languages
 Low level languages
 Machine-dependent runs only on one type of computer
 Close to the language which computers can read
 Ex: Machine and Assembly Languages
 High level languages
 Often machine-independent can run on many different types of
computers and operating systems
 Close to the language which we can read

Low-Level Languages
Machine Language
 Only language computer directly recognizes
 Most efficient
 Uses a series of binary digits (1s and 0s) with a
combination of numbers and letters that represent
binary digits
0111 0001 0000 1111
1001 1101 1011 0001

Low-Level Languages (con’t)
Assembly Language
 Instructions made up of symbolic instruction codes,
meaningful abbreviations and codes
 Source program contains code to be converted to
machine language
MOV AX 01
MOV BX 02
ADD AX BX

High-Level Languages
 High Level Languages are more close to our
human’s languages.
 They are also referred as Half-English
programming languages.
 The programs have to be converted or complied to
the machine languages.
 Less efficient but more programmer friendly
 Examples: Basic、C/C++、C#、Java、FORTRAN、
COBOL, Pascal and so on.

High-Level Languages (con’t)
There are two basic approaches to implementing a
program in a higher-level language:
Compilers
 A source program is converted into machine language
before being executed.
 A source program will be inspected the syntax before
being complied.

High-Level Languages (con’t)
Interpreters
 Translates and executes one program code statement
at a time
 Less efficient
 Easy to find errors and flexible
 Examples: Web programming languages -Scripts
(VBScript and JavaScript)

Execution of Programs
 When CPU executes a machine language program, it
read the instructions stored in memory (RAMs) and
execute (Fetch-and-execute).
 CPU fetches the instructions sequentially.
 CPU can NOT understand what a program wants to do.
It just computes very fast.

Central Processing Unit
The CPU consists of a variety of parts including:
 Control unit: directs the other parts of the
computer system to execute stored program
instructions.
 Arithmetic and Logic Unit (ALU): performs
mathematical operations as well as logical
operations.
 Registers: are temporary storage areas for data or
instructions. For example: to add two numbers
which are stored at registers.

Random-Access Memory
 Before the CPU can execute a program, program
instructions and data must be placed into memory
from an input device or storage device.
 Memory is the part of the computer that stores
data and program instructions for processing.
 Once the necessary data and instructions are in
memory, the CPU performs “Fetch and Execute”.
 Each location in memory is identified by an
address.
 The control unit can find data and instructions
based on these addresses.

Example: Execution of Programs
 k← i + j
 retrieve i
 retrieve j
 perform i+j
 store the result to k

Introduction of C#
 .NET Framework
 C#
 Vision Studio 2010

.NET Framework
 .NET Framework is the latest programming develop
platform offered by Microsoft.
 The current version is 4.0.
 The class library and the Common Language Runtime
(CLR) together constitute the .NET Framework.
 Users can use Visual Basic, C++, and C# to write
programs based on .NET Framework.
 Programs developed on .NET Framework are not
complied to machine language, but intermediate byte-
code called “MSIL” (Microsoft Intermediate Language)。

.NET Framework (con’t)
 When execution of the byte-code, MSIL is JIT(Just
In Time) complied to machine language by CLR.
2010
7

C#
 C# (C Sharp) is developed by the team leaded by
Anders Hejlsberg
 C# is introduced on 2000 and released on 2002
 Object-oriented programming language based on C++
 Accepted as a standard for Web applications and XML-
based Web services
 Uses a JIT compiler
 Resulting code is called Microsoft Intermediate
Language (MSIL)

Visual Studio
 Development Environment
 A set of tools which provides programmers to build, edit,
compile, and maintain programs
 Currently, most of high-level languages have their own
development environment, which is referred to as IDE
(Integrated Development Environment).
 IDE is a software application which enables
programmers to edit source codes, compile, debug,
and manage programs throughout software
development.

Visual Studio (con’t)
 What is Visual Studio?
 .NET is set of technologies that allows program to run
on Internet
 Comprised of Visual Basic, Visual C++, Visual C#, and
Visual J#
 Visual Studio 2005/2008/2010 is an Integrated
Development Environment (IDE) from Microsoft
 Visual Studio 2005/2008/2010 is an IDE which
supports .NET Framework. It can be used to develop
various types of applications for Windows, ASP.NET,
console, and Web Services.

 Applications developed in IDE of Visual Studio are
executed on the CLR platform of .NET Framework:
/2010
4.

 The functions of Visual Studio
 IDE for multiple programming languages
 Powerful functions of project management
 Project templates are offered
 Visual program-developing GUI
 IntelliSense-autocompletion
 Complete functions of debugger

Introduction to Computer Programming (general background)

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