C＃/. Net phase VI 01C Foundation_ 02:vs2019 basic operations, excluding code files, smart tips, data types, differences between float and double, and differences between string and string

List of articles

Smart tips

Red wavy line ： Compile error prompt ( Compile not pass )
Yellow wavy line ： Warning tips ( Out of date )
Green wavy line : Not used ( Extra code , You can delete )

Debug 、Release What is it?

In fact, when you click start, you will
Execute build first , Restart ,
So it actually seems like a step , In fact, two operations are performed automatically

Project type ：
1、Debug Debug version （ Usually in the development stage is this version ）
2、Release The release （ Official version ）

*exe.config This is the one in the project App.config, It should be noted that .netCore/.Net5 Then it was a little different , It's been like this before

1、Debug Debug version （ Usually in the development stage is this version ）
2、Release The release （ Official version ）
The difference between them is , In fact, the operation effect is the same ,
It's just Release Some underlying information will not be displayed , The user experience will be friendly when an error is reported

The function is as like as two peas. , After all, the code is the same

Some documents explain

App.config What is written in it will not be compiled , There are some configurations recorded
What is recorded here is The environment in which our program runs

The workbench does not display irrelevant files , Like the one above

If you don't want to see a file on the workbench
You can also receive exclusions , as follows （ Be careful , Exclusion will not delete ）

After exclusion from the project , If you regret it again , It's fine too

Why should there be an exclusion function

Because sometimes if our code is wrong , But I don't want to delete , Useful words ,
We can actually use this function , In this way, you can compile , Otherwise, the compilation fails , It doesn't work
I found the problem of the code later , Just add it in
The following two can also be deleted , Because these two versions are compiled ,
It means that it can be regenerated , As long as the code is , No problem at all

Main method

The formal parameters in this , It's actually useless at present , In fact, it can be deleted , It is only generated by default when generating

How to be in vs Running programs inside

Shortcut key ：
function ：
F5
Ctrl+F5

Suggestions when learning the console Ctrl+F5
Ctrl+F5, Wait in the console

Receiving user information

\t tabs ,, Similar to spaces

data type

Why data types

1、 In order to maximize the rational allocation of resources （ Save memory ）

The smallest unit of a computer
Namely 0 and 1 Bit
1Byte=8 The bit

1 Byte = 8 bit （ A byte is equal to 8 A bit ）

1b and 1kb Is that what I mean

It's not

1b It's actually very small
1kb=1024b
1Mb=1024kb
1GB=1024MB
1TB=1024GB （ At present, the maximum capacity of hard disk is basically in this unit capacity ）
1PB=1024T Billions of bytes
……

Why data types

For example , What data type does money use
float（ Ordinary people ）、double、decimal（ Bill Gates, ）
Age , Actually use short That's enough. , There should be no more than 1000 Years old

Reasonable application of data types can save memory
Of course , Be reasonable, as shown in the figure above , Otherwise you will report an error
such as

float and double The difference between

double Because the default is double type , So you don't have to add d There's no need for
and float Smaller
float > dolble > decimal

Suggest
When describing a student's score , Suggest using float
Describe the bank's huge amount of money decimal
There are differences between theory and Practice , That makes sense , Habit is a terrible thing
In theory, age should be short More reasonable , But in fact, we rarely tangle with this problem , In the actual development process, age is generally used int data type

uppercase String And lowercase string What's the difference?

stay java There are very strict distinctions ,
Only capitalized String, No lowercase string
StringBuider（ Thread unsafe , Highest efficiency , For single pass
StringBuffer（ Thread safety , Efficient than String high , Multithreading ）

stay Java Inside Basically in uppercase String, Because uppercase is a wrapper class , Lowercase is a variable type
and C# Inside , Basically in lowercase string, And capital letters can also , Capitalization String And lowercase string There is no difference in use
The only difference is String yes C# Framework .net framework Provided ,string yes C# Provided by itself ,, Usage in C# There is no difference
Why is it C# We used to use lowercase in it string Well , This is because lowercase string, We don't need to introduce any libraries , It can be used directly
C# It's basically in lowercase string（ There is no difference in case and function ）

bool data type

Summary

Red wavy line ： Compile error prompt ( Compile not pass )
Yellow wavy line ： Warning tips ( Out of date )
Green wavy line : Not used ( Extra code , You can delete )

Project type ：
1、Debug Debug version
2、Release The release

function ：F5
Ctrl+F5