Introduction to commonly used built-in packages in Go language

I. Overview

The Go language has built-in packages with many commonly used functions, which can be directly used for project development. Proficiency in built-in packages can greatly improve the efficiency of Go language programming.

This article will briefly introduce some commonly used built-in packages in the Go language, including

• fmt package: formatting and printing
• os package: platform related functions
• io package: input and output operations
• bufio package: cached IO
• net/http package: HTTP network communication
• encoding package: data encoding and decoding
• flag package: command line parameter parsing
• reflect package: reflection mechanism
• sort package: sorting functions
• testing package: testing framework

2. fmt package

The fmt package implements formatted IO related functions:

• Print series functions print output
• Scan series function format input
• Sprintf formatted string concatenation
• Errorf error creation

3. os package

The os package provides platform-dependent functions:

• File operations: open, delete, rename files
• Directory operations: create and delete directories
• Environment variables: getting and setting environment variables
• Process/command operations: start processes, etc.

Cross-platform code can be written using the os package.

4. io package

The io package provides basic IO primitives:

• Reader/Writer interface
• Pipe pipe communication
• EOF end flag
• LimitedReader reads according to restrictions

The io package defines an abstract interface for all IO operations.

5. bufio package

bufio implements buffered IO operations:

• Buffering reading and writing improves efficiency
• Read, Write series methods
• Custom buffer read and write objects
• Expandable buffering

Suitable for IO operation optimization.

6. net/http package

The net/http package provides HTTP client and server implementations:

• Client sends request
• Server handles the request
• Transport underlying transport
• response/request object
• timeout mechanism

Many web services are built on the net/http package.

7. encoding package

encoding implements various data encoding and decoding:

• JSON encoding and decoding
• XML encoding and decoding
• Base64 encoding and decoding

The encoding package can be used in daily encoding conversion scenarios. 

8. flag package

The flag package implements command line parameter parsing:

• Define command line flag parameters
• Parse command line input parameters
• Commonly used flag types (bool, int, etc.)
• Custom flag type

Many CLI tools use the flag package.

9. reflect package

reflect implements the reflection mechanism:

• TypeOf reflection type information
• ValueOf reflection value information
• Setting variables via reflection
• Reflection calling method

Reflection is an important capability of dynamic languages.

10. sort package

The sort package implements various data sorting:

• Sort slices of built-in types
• Sort custom types
• Sort by multiple conditions
• Stability ranking

Just implement a few interfaces to sort.

11. Testing package

testing provides testing functions:

• Add test case
• Run tests and generate reports
• coverage calculation
• benchmark stress test
• mock data

Can write unit tests etc.

Summarize

Go language has many commonly used packages built-in, and rational use can greatly improve development efficiency. This article provides a brief overview of some of them, hoping to help you better use the built-in packages of the Go language.