First knowledge of UML, teach you first taste

First knowledge of UML, teach you first taste

UML, full name: Unified Modeling Language, Unified Modeling Language. It is a standard modeling language for software and system development. It mainly analyzes and designs the system in a graphical manner. At the same time, UML is neither a programming language nor a formal language, but a visual modeling language.

From the diagram, we can basically understand the basic concepts of UML, the most important of which is the relationship and diagram in the basic structure.

Relationship: represents the relationship between basic symbols or things.

Association: represented by a horizontal line

Dependency: add an arrow to the dotted line to indicate the dependency between items. The arrow points to the dependent object.

Generalization: a line is composed of a hollow triangle frame. It can also be called inheritance.

Implementation: The dotted line is added with a hollow triangle, and the class is at the dotted line end.

Drawing can be said to be the most important module. UML is to make developers better understand the program to be developed through drawing. Therefore, drawing is the focus and difficulty of our learning. First, we will briefly introduce the basic concepts of each graph:

Use case diagram: used to describe the user's needs, describe the system's functions from the user's perspective, and point out the executors of the Functions

Class diagram: defines the class in the system, including describing the internal structure of the class and the relationship between the class. Class diagrams are mainly used to describe the static structure of the system.

Object graph: an instance of a class graph that describes the objects contained by the system at a specific time point and the relationships between objects.

Status chart: Describes all possible states of the Class Object and transfer conditions of the State when an event occurs.

Activity diagram: used to describe the activities that meet the requirements of use cases and the constraint relationships between activities. It is used to identify parallel activities of the system.

Sequence diagram: Describes the interaction sequence between objects.

Collaboration diagram: partnerships between objects

Component diagram: physical structure of code components and dependencies between components

Deployment diagram: defines the physical architecture of hardware in the system, which is used to describe the actual physical devices and their connection relationships.

We are still watching the video of UML. We need to learn more about it. However, with this open-door learning, I can deeply feel that the preparation of the documents we learned previously is a stepping stone for us to step into a higher position by programmers, this allows us to pay attention to the details that we did not pay attention to when writing code. The learning of UML is to help us better understand the software we want to develop. In addition, it can also be understood by those who do not understand programming. The more you learn, the higher you will feel. In this case, work hard, fighting...

I was just getting started with UML, but I still don't know much about it. If you have any shortcomings, I hope you can give us some guidance and make common progress.

How to Learn delphi

To learn about Delphi, you must first understand its controls and its development mode. What is more difficult is how to understand so many controls. In my Delphi, there are already more than 10 thousand controls. It is impossible to use them all, generally, it is just what needs to be used. Fortunately, the help document of Delphi writes the control in details. You only need to select a control and then press F1.

Reading help documentation also requires some skills. For example, Windows API does not exist in the help documentation of Delphi. You need to download MSDN and Linux API contains it in the Help file, so there is no need to go online again. If you press F1 and the system prompts that you have not found the content to be found, you can choose to turn to or configure the Help file.

For example, if you search for IWButton, the system will prompt you that you cannot find the relevant items, and a redirection will appear, prompting you to switch to the possible entry. You can switch to the IntraWeb entry to see it. If the IntraWeb entry is not found, you can use the Delphi help tool for configuration, find the IntraWeb help file, such as IW6.hlp, and add it to the Delphi help file. After adding the file, save it and search again.

Of course, you can't just look at help. You need to do more practical things, and the concept of object-oriented is very important. Although Delphi supports process-oriented, in most cases, development must be object-oriented. Concepts like class and interface must be fully understood. For some external program calls, you must also understand the relevant knowledge of COM.

There are also some conceptual issues. Many people think that Delphi cannot develop webpages. This is a wrong idea. Like Delphi, it can develop beautiful websites, its beauty level and functionality are as powerful as those made by DreamWaver. And the most important thing is its fast development speed. Delphi is the best choice if you have enough space on your host and a large limit on development time. Developing a website with Delphi is exactly the same as developing a WinForm application. It only converts the development mode to WebSnap, IntraWeb, ExpressWeb or Delphi Script.

As a qualified Delphi programmer, you must also understand the relevant Assembly knowledge. Delphi is open-source, but more than half of its open-source components are written in assembly code. If you do not understand it, this will inevitably have a certain impact on development. Suppose you need to understand the working principle of the serial control to rewrite it, but the control is compiled by sink, which causes trouble for developers who do not understand assembly. Of course, I don't want you to learn how well the assembly is. You have to learn more C at the time of the compilation, but you must know the basic concepts, such as registers and Invoke.

Finally, let's talk about the future of Delphi. As far as I can see, Delphi programmers are very popular. In most software companies, they hope programmers can independently complete complex development, therefore, a large number of Delphi programmers will be recruited. This happened in Shanghai, where a large number of C ++ and Java programmers were dismissed and a small number of Delphi programmers were recruited, because at the same technical level, A Delphi programmer can complete five Java programmers within one week in one month.

In some large projects, cooperation between developers is also required, but the tacit understanding of Delphi programmers is much higher than that of C ++ programmers. If you develop a project in cooperation mode, therefore, you must create and release interfaces. Otherwise, Delphi does not allow compilation of cooperative projects, which makes the code between developers very normative and can generate UML diagrams according to the project plan, this greatly simplifies the development process. There are many companies that need Delphi programmers.

Therefore, Delphi is useful in actual development, but you should never use Delphi when learning programming ideas, which will be very unfavorable to you. Keep this in mind. Delphi should be proficient only when it is used for multiple purposes. When you can make your own... the rest of the text>

How to Learn C #

1: First familiar with the C # syntax. I have learned it before. Just use the console program once.
2: learn basic object-oriented concepts, inheritance, polymorphism, etc.
3: winform basics, form machines, and controls
4: Learn how to connect to the database with ado.net (prerequisite: Database basics)
----- This is the foundation.
5: asp.net
6: mvc
7 ....

It is not feasible to read or not practice.