Detailed explanation of the application of iota in Go language

Preface

When you study the official website library, open source library or any oneGoWhen you are projected, you will findiotaThis magical identifier is everywhere. It plays an important role in making the code more concise, clear, and improves readability and maintainability. Its application range is a wide range of applications, from enum types to position operations to complex constant expression calculations, and it can do everything.

In this article, I will take you to discuss it in depthiotaThe magical powers includeiotaIntroduction and application scenarios, usage tips and precautions.

Ready? Prepare a cup of your favorite drink or tea and find out with this article.

iota introduction

Within a constant declaration, the predeclared identifier iota represents successive untyped integer constants. Its value is the index of the respective ConstSpec in that constant declaration, starting at zero.

The above quotation comes from the official website document, and the original words translated into Chinese means:

In a constant declaration, a pre-declared identifieriotaRepresents continuous untyped integer constants. Its value is the corresponding one in the constant declarationConstSpecIndex, counting from zero.

In short, by usingiota, We can automatically create a series of continuous integer values ​​in a constant declaration, with values ​​starting from zero without manually specifying the value of each constant.

Application scenarios of iota

Automatically generate incremental constant values

useiotaIt is easy to generate incremental constant values. The first use in a constant declarationiotaThe constants are initialized to0, and the values ​​of the constants that appear will automatically increment, which makes it easier to manually specify the value of each constant when defining a set of incrementing constants, which improves the code'sreadabilityHekeMaintenance. For example:

const (
	Apple  = iota // 0
	Banana        // 1
	Cherry        // 2
)

Build enum type constants

By usingiotaA series of relevant enum values ​​can be easily defined without manually specifying specific numbers for each value. Such enumeration types are more concise and easy to expand and modify. For example:

type WeekDay int
const (
	Sunday    WeekDay = iota // 0
	Tuesday                  // 1
	Wednesday                // 2
	Thursday                 // 3
	Friday                   // 4
	Saturday                 // 5
	Monday                   // 6
)

If you want to know more detailed enum usage, go toThere is no enum type in Go, but we can do thisRead.

Expression calculation

By using it in constant declarationiota, complex expressions can be created and adjusted as needed in each constant declarationiotavalue. This makes it easy to generate a set of constants with specific rules. For example:

const (
	_  = iota
	KB = 1 << (10 * iota) // 1 << (10 * 1) = 1024B = 1KB
	MB = 1 << (10 * iota) // 1 << (10 * 2) = 1048576B = 1MB
	GB = 1 << (10 * iota) // 1 << (10 * 3) = 1073741824B = 1GB
	TB = 1 << (10 * iota) // 1 << (10 * 4) = 1099511627776B = 1TB
)

Bit operation

By left shift operator (<<)andiotaUsed in conjunction with it, conveniently generate a set of constants for bitwise operations. For example:

const (
	FlagNone  = 0         // 0
	FlagRead  = 1 << iota // 1
	FlagWrite             // 2
	FlagExec              // 4
)

Tips and precautions for using iota

Use jump value

We can use_(underscore) to ignore certain values, for example:

const (
	Apple = iota// 0
	_
	Banana // 2
)

Different constant blocks, iota is independent

iotaThe scope of action is the entire constant block, different constant blocksiotais independent, the first of each constant blockiotaThe values ​​are all0。

const (
	A = iota // 0
	B        // 1
)
const (
	C = iota // 0
	D        // 1
)

summary

This article is aboutiotaMake a detailed introduction and make full use ofiotaThe feature of writing code can make the code more concise and clear, while also improving readability and maintainability.

This is the end of this article about detailed explanation of the application of iota in Go. For more related iota content in Go, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!