C#编程入门：黄皮书精华

需积分: 10 71 浏览量更新于2024-07-26 收藏 2.76MB PDF 举报

"CSharp_Yellow_Book 是一本关于C#编程的著作，由Rob Miles撰写，属于第二版，由英国赫尔大学计算机科学系出版。这本书涵盖了计算机基础、程序设计、编程语言、C#语言特性、简单数据处理、程序创建、解决方案构建以及高级编程等多个方面。" 在《CSharp_Yellow_Book》中，作者首先介绍了计算机的基础知识，包括计算机的工作原理和程序与编程的区别。他指出，计算机是执行预设指令的机器，而编程则是为了创造出这些指令，使计算机能够执行特定任务。编程语言是人与计算机沟通的桥梁，C#作为一门面向对象的语言，是.NET框架的重要组成部分，广泛应用于Windows应用开发、ASP.NET web应用开发等领域。第二部分深入讲解了简单数据处理。读者将学习如何编写第一个C#程序，以及如何处理和操纵数据。这部分内容涵盖了变量的声明和使用、数据类型转换、条件判断和循环控制等基础知识，帮助初学者掌握基础编程技巧。第三部分介绍了如何创建更复杂的程序，涉及方法的定义与调用、变量的作用域、数组的使用、异常处理、switch语句以及文件操作。这些概念是构建大型程序的基础，特别是异常处理和文件操作，它们使得程序能更好地应对错误情况并实现数据持久化。第四部分侧重于如何构建解决方案，通过一个案例——“FriendlyBank”来展示。书中详细解释了枚举类型、结构体、对象与引用的区别、面向对象设计原则、静态成员、对象构造以及组件化编程。此外，还讨论了继承的概念，这是面向对象编程中的重要特性，增强了代码的复用性和灵活性。最后，作者讨论了字符串和字符的强大功能，以及属性的使用，这些都是C#中处理数据的关键工具。第五部分探讨了高级编程主题，如泛型和集合的使用，这可以提高代码的通用性。同时，书中的内容还包括如何存储业务对象，这在实际应用开发中非常重要，因为业务对象通常需要被有效地管理和检索。《CSharp_Yellow_Book》是一本全面介绍C#编程的教材，适合初学者和有一定经验的开发者阅读。它不仅提供了理论知识，还通过丰富的示例和实战练习帮助读者巩固所学，从而提升编程技能。

Computers and Programs C#

C# Programming © Rob Miles 2010 15

with it. Switching to unmanaged mode is analogous to removing the guard from your

new chainsaw because it gets in the way.

C# is a great language to start learning with as the managed parts will make it easier for

you to understand what has happened when your programs go wrong.

1.4.3 C# and Objects

The C# language is object oriented. Objects are an organisational mechanism which let

you break your program down into sensible chunks, each of which is in charge of part

of the overall system. Object Oriented Design makes large projects much easier to

design, test and extend. It also lets you create programs which can have a high degree

of reliability and stability.

I am very keen on object oriented programming, but I am not going to tell you much

about it just yet. This is not because I don't know much about it (honest) but because I

believe that there are some very fundamental programming issues which need to be

addressed before we make use of objects in our programs.

The use of objects is as much about design as programming, and we have to know how

to program before we can design larger systems.

1.4.4 Making C# Run

You actually write the

program using some form of

text editor - which may be

part of the compiling and

running system.

C# is a compiled programming language. The computer cannot understand the

language directly, so a program called a compiler converts the C# text into the low

level instructions which are much simpler. These low level instructions are in turn

converted into the actual commands to drive the hardware which runs your program.

We will look in more detail at this aspect of how C# programs work a little later, for

now the thing to remember is that you need to show your wonderful C# program to

the compiler before you get to actually run it.

A compiler is a very large program which knows how to decide if your program is

legal. The first thing it does is check for errors in the way that you have used the

language itself. Only if no errors are found by the compiler will it produce any output.

The compiler will also flag up warnings which occur when it notices that you have

done something which is not technically illegal, but may indicate that you have made a

mistake somewhere. An example of a warning situation is where you create something

but don't use it for anything. The compiler would tell you about this, in case you had

forgotten to add a bit of your program.

The C# language is supplied with a whole bunch of other stuff (to use a technical term)

which lets C# programs do things like read text from the keyboard, print on the screen,

set up network connections and the like. These extra features are available to your C#

program but you must explicitly ask for them. They are then located automatically

when your program runs. Later on we will look at how you can break a program of

your own down into a number of different chunks (perhaps so several different

programmers can work on it).

1.4.5 Creating C# Programs

Microsoft has made a tool called Visual Studio, which is a great place to write

programs. It comprises the compiler, along with an integrated editor, and debugger. It

is provided in a number of versions with different feature sets. There is a free version,

called Visual Studio Express edition, which is a great place to get started. Another free

resources is the Microsoft .NET Framework. This provides a bunch of command line

tools, i.e. things that you type to the command prompt, which can be used to compile

and run C# programs. How you create and run your programs is up to you.

Computers and Programs C#

C# Programming © Rob Miles 2010 16

I'm not going to go into details of how to download and install the .NET framework;

that is for other documents, I am going to assume that you are using a computer which

has a text editor (usually Notepad) and the .NET framework installed.

The Human Computer

Of course initially it is best if we just work through your programs on paper. I reckon

that you write programs best when you are not sitting at the computer, i.e. the best

approach is to write (or at least map out) your solution on paper a long way away from

the machine. Once you are sitting in front of the keyboard there is a great temptation to

start pressing keys and typing something in which might work. This is not good

technique. You will almost certainly end up with something which almost works,

which you will then spend hours fiddling with to get it going.

If you had sat down with a pencil and worked out the solution first you would probably

get to a working system in around half the time.

Programmer’s Point: Great Programmers debug less

I am not impressed by hacking programmers who spend whole days at terminals fighting with enormous programs

and debugging them into shape. I am impressed by someone who turns up, types in the program and makes it work

first time!

1.4.6 What Comprises a C# Program?

If your mum wanted to tell you how to make your favourite fruitcake she’d write the

recipe down on a piece of paper. The recipe would be a list of ingredients followed by

a sequence of actions to perform on them.

A program can be regarded as a recipe, but written for a computer to follow, not a

cook. The ingredients will be values (called variables) that you want your program to

work with. The program itself will be a sequence of actions (called statements) that are

to be followed by the computer. Rather than writing the program down on a piece of

paper you instead put it into a file on the computer, often called a source file.

This is what the compiler acts on. A source file contains three things:



instructions to the compiler



information about the structures which will hold the data to be stored and

manipulated.



instructions which manipulate the data.

To take these in turn:

Controlling the Compiler

The C# compiler needs to know certain things about your program. It needs to know

which external resources your program is going to use. It also can be told about any

options for the construction of your program which are important. Some parts of

your program will simply provide this information to tell the compiler what to do.

Storing the Data

Programs work by processing data. The data has to be stored within the computer

whilst the program processes it. All computer languages support variables of one form

or another. A variable is simply a named location in which a value is held whilst the

program runs. C# also lets you build up structures which can hold more than one item,

for example a single structure could hold all the information about a particular bank

customer. As part of the program design process you will need to decide what items of

data need to be stored. You must also decide on sensible names that you will use to

identify these items.

Computers and Programs C#

C# Programming © Rob Miles 2010 17

Describing the Solution

The actual instructions which describe your solution to the problem must also be part

of your program. A single, simple, instruction to do something is in a C# program is

called a statement. A statement is an instruction to perform one particular operation, for

example add two numbers together and store the result.

The really gripping thing about programs is that some statements can change which

statement is performed next, so that your program can look at things and decide what

to do. In the case of C# you can lump statements together to form a lump of program

which does one particular task. Such a lump is called a method.

Seasoned programmers break

down a problem into a

number of smaller ones and

make a method for each.

A method can be very small, or very large. It can return a value which may or may

not be of interest. It can have any name you like, and your program can contain as

many methods as you see fit. One method may refer to others. The C# language also

has a huge number of libraries available which you can use. These save you from

"re-inventing the wheel" each time you write a program. We will look at methods in

detail later in these notes.

Identifiers and Keywords

You give a name to each method that you create, and you try to make the name of the

function fit what it does, for example ShowMenu or SaveToFile. The C# language

actually runs your program by looking for a method with a special name, Main. This

method is called when your program starts running, and when Main finishes, your

program ends. The names that you invent to identify things are called identifiers. You

also create identifiers when you make things to hold values; woodLength might a

good choice when we want to hold the length of wood required. Later on we will look

at the rules and conventions which you must observe when you create identifiers.

The words which are part of the C# language itself are called keywords. In a recipe a

keyword would be something like "mix" or "heat" or "until". They would let you say

things like "heat sugar until molten" or "mix until smooth". In fact, you'll find that

programs look a lot like recipes. Keywords will appear blue in some of the listings in

this text.

Objects

Some of the things in the programs that we write are objects that are part of the

framework we are using. To continue our cooking analogy, these are things like mixing

bowls and ovens, which are used during the cooking process. The names of objects will

be given in a different shade of blue in some of the listings in this text.

Text in a Computer Program

There are two kinds of text in your program. There are the instructions that you want

the computer to perform and there are the messages that you want the program to

actually display in front of the user. Your mum might add the following instruction to

her cake recipe:

Now write the words “Happy Christmas” on top of the cake in pink icing.

She is using double quote characters to mark the text that is to be drawn on the cake,

and C# works in exactly the same way. ―Happy Christmas‖ is not part of the

instructions; it is what needs to be written. These kinds of messages are coloured red

in this text.

Colours and Conventions

The colours that I use in this text are intended to line up with the colours you will see

when you edit your programs using a professional program editor such as the one

supplied as part of Visual Studio. The colours just serve to make the programs easier to

understand, and do not have any special meaning. They are added automatically by the

editor as you write your program.

Simple Data Processing A First C# Program

using System;

A big part of learning to

program is learning how to

use all the additional features

of the system which support

your programs.

This is an instruction to the C# compiler to tell it that we want to use things from the

System namespace. A namespace is a place where particular names have meaning.

We have namespaces in our conversations too, if I am using the "Football"

namespace and I say “That team is really on fire” I'm saying something good. If I

am using the "Firefighter" namespace I'm saying something less good.

In the case of C# the System namespace is where lots of useful things are described.

One of these useful things provided with C# is the Console object which will let me

write things which will appear on the screen in front of the user. If I want to just refer

to this as Console I have to tell the compiler I'm using the System namespace. This

means that if I refer to something by a particular name the compiler will look in

System to see if there is anything matching that name. We will use other namespaces

later on.

class GlazerCalc

Classes are the basis of object

oriented programming, as we

shall see later.

A C# program is made up of one or more classes. A class is a container which holds

data and program code to do a particular job. In the case of our double glazing

calculator the class just contains a single method which will work out our wood

lengths and glass area, but a class can contain much more than that if it needs to.

You need to invent an identifier for every class that you create. I've called ours

GlazerCalc since this reflects what it does. For now, don't worry too much about

classes; just make sure that you pick sensible names for the classes that you create.

Oh, and one other thing. There is a convention that the name of the file which contains

a particular class should match the class itself, in other words the program above

should be held in a file called GlazerCalc.cs.

static

This keyword makes sure that the method which follows is always present, i.e. the

word static in this context means "is part of the enclosing class and is always

here". When we get to consider objects we will find that this little keyword has all

kinds of interesting ramifications. But for now I'd be grateful if you'd just make sure

that you put it here in order to make your programs work properly.

void

A void is nothing. In programming terms the void keyword means that the method

we are about to describe does not return anything of interest to us. The method will

just do a job and then finish. In some cases we write methods which return a result

(in fact we will use such a method later in the program).

However, in order to stop someone else accidentally making use of the value

returned by our Main method, we are explicitly stating that it returns nothing. This

makes our programs safer, in that the compiler now knows that if someone tries to

use the value returned by this method, this must be a mistake.

Main

You choose the names of your methods to reflect what they are going to do for you.

Except for Main. This method (and there must be one, and only one such method) is

where your program starts running. When your program is loaded and run the first

method given control is the one called Main. If you miss out the Main method the

system quite literally does not know where to start.

剩余196页未读，继续阅读

txp914

粉丝: 22
资源: 703

C#编程入门：黄皮书精华

Yellow-Submarine

Siemens_Simatic_Step7_V5.4_Yellow_Disk_2006_05_05

yellowgrid:这样的超级网格

MO_CSharp.rar_MO_CSharp_MapObjects_Mapobjects CSharp_mapobjects

GPRS.rar_Csharp GPRS_GPRS CSharp_QQ Csharp_gprs 51

ftp.rar_FTP CSharp_FTP server CSharp_csharp FTP_ftp_ftp 服务器

ist的matlab代码-csharp_samples_collections_event-calendar:csharp_samples_c

ERP.rar_.net ERP_ERP_ERP CSharp_ERP CSharp_erp .net

Csharp_video_sound.rar_C#语音传输_Csharp_video_sound_c#语音转文字_视频语音聊天

UHFReader09demomain.rar_DEMO_UHF CSHARP_UHFReader09CSharp_UHFRea

最新资源