This is the second part of Go Zero, mainly about Go naming conventions, variables and constants.
Naming conventions
In Go, any identifier (variable, constant, function, custom type, etc.) should comply with the following rules:
- A sequence of characters or numbers.
- Starts with a character or underscore.
- Cannot conflict with the Go keyword.
The keyword
The Go language has a total of 25 keywords. As follows:
break default func interface select
case defer go map struct
chan else goto package switch
const fallthrough if range type
continue for import return var
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So let’s take a look at which names are legal based on these points
foo # legal
foo1 # legal
_foo # legalvariableIt is not recommended to use Chinese names
1foo # illegal
1 # illegal
type # illegal
a+b # illegal
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variable
In the Go language, the common form for declaring variables is to use the VAR keyword: var Identifier Type. Such as:
var a int
var b bool
var str string
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We can also declare:
var (
a int
b bool
str string
)
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This factorization keyword is used to declare global variables.
When a variable is declared, it is automatically given a zero value of that type: int 0, float 0.0, bool false, string empty string, and pointer nil. Remember, all internals are initialized in Go.
Of course, declarations and assignment (initialization) statements can also be combined. Such as:
var a int = 15
var i = 5
var b bool = false
var str string = "Go says hello to the world!"
var (
a = 15
b = false
str = "Go says hello to the world!"
numShips = 50
city string
)
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At this point, we can omit the type of the variable because the Go compiler can automatically infer its type from its value.
Short statement
If a variable has an initial value, we can use a short declaration like := :
A := 1 // Declare a as an integer of 1Copy the code
This method can only be used in functions and will cause errors when used in global variable declarations.
constant
Constants are used to store data that does not change. It is defined in a similar way to variables. Constants are defined using the const keyword: const identifier [type] = value. Constants are defined according to the following rules:
- A value must be assigned when declared.
- Data types stored in constants can only be Boolean, numeric (integer, floating point, and complex), and string.
- Cannot be declared with :=.
Such as:
Const a = 64 const (b = 4 c = 0.1) Monday, Tuesday, Wednesday, Thursday, Friday, Saturday = 1, 2, 3, 4, 5, 6 const ( Monday, Tuesday, Wednesday = 1, 2, 3 Thursday, Friday, Saturday = 4, 5, 6 )Copy the code
Afterword.
I am just a beginner of Go language, this article may have mistakes, welcome everyone to comment area exchange.