Go learn 02 basic knowledge

1.golang Classification of annotations in

• Line notes , Shortcut key Ctrl+/  , Uncomment the same

• Block annotation , Shortcut key Alt+Shift+A, Uncomment the same  

All programming language annotations are similar  

2. Variable definitions , Use it directly var receive ,go Infer the variable type by yourself . 

  image C# Some programming languages , When you define a variable, you need to specify the variable type , for example string msg="hello go", Now you can use it directly var To replace ,var Is what your value type is , What type it returns .

2.1 Variable range  

• Package level variables , It's a global variable , It can be used in all methods of the current program .
• Function level variables , It's a local variable , Can only be used within the current method .

Be careful ： stay Go in , The same variable name is allowed , But in other languages , for example C# The same variable name is not allowed . And in Go in , There is a variable name with the same name , Function level variable names have the highest priority .

 

  

2.2 Variable declaration method  

• var Mode of declaration , Automatically infer variable types from values , There is an introduction above
• Short notice , Use the mask : Statement No , It also automatically infers variable types

Be careful ：1. The variable name of a short declaration must be unique , The same short declaration variable cannot and will not exist , Because it will directly prompt the error , for example ：

 

 2. The short declaration must be defined in the function body to use , Cannot be at package level ( overall situation ) Define the use of .

 2.3 Merging of variables

Why should variables be merged , Is to reduce the amount of code and beautiful , It can also achieve the same effect as defining multiple variables .

example 1： When we need to define multiple short declaration variables , It is usually defined as .

But it can be defined in this way ：

  example 2： Normal multiple variables are generally defined in this way

But in fact , It can be like this , 

 

  Even importing multiple packages can be written in this form

  Be careful ： Variables defined in the function body , You have to use . If it is not used, it will prompt an error

 

 2.4 Variable naming conventions

1. It can't be go Key words of
2. Cannot start with a number
3. Variable names can only consist of strings , Numbers , Underline composition
4. Variable declaration uses hump specification , Or several English combinations , for example ：hello_world or helloWorld
5. Variable names are case sensitive , for example ：Hello and hello It's two different variable names

See the official website for details  Go Language course | Novice tutorial (runoob.com)