Golang: Package, Import

By Xah Lee. Date: . Last updated: .

Every Go program is made up of packages.

Programs start running in package named “main”, with function “main”.

package main

import "fmt"

func main() {
	fmt.Println(3 + 4) // 7
}

Import

import name → import a package named name

The name should be a string.

package main

import "fmt"
import "math"

func main() {
	fmt.Printf("%v\n", math.Sqrt(9)) // 3
}

alternative syntax:

import (name1; name2 etc)

package main

import (
	"fmt"
	"math"
)

func main() {
	fmt.Printf("%v\n", math.Sqrt(9)) // 3
}

Semicolon Optional

Semicolon ; is optional when it is at end of line.

There is a command line tool , named “gofmt”, that automatically reformat your go source code to a standard format.

Exported Names, Begin with Upper Case

A name is exported if it begins with a capital letter.

When importing a package, you can refer only to its exported names. Any “unexported” names are not accessible from outside the package.

Reference

The Go Programming Language Specification - The Go Programming Language#Packages

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Golang

  1. Compile, Run
  2. Source Encoding
  3. Package, Import
  4. Comment
  5. Print
  6. String
  7. String Functions
  8. Print String
  9. String Backslash Escape
  10. Rune
  11. Variable
  12. Zero Value
  13. Constant
  14. If Then Else
  15. Switch/Case
  16. Loop
  17. Basic Types
  18. Array
  19. Slice
  20. Map
  21. Struct
  22. Function
  23. Closure
  24. Pointer
  25. String, Byte Slice, Rune Slice
  26. regexp
  27. Read File
  28. Write to File
  29. Walk Dir
  30. Check File Exist
  31. System Call
  32. Get Script Path
  33. Defer
  34. Random Number

Examples

  1. Match Any Regexp
  2. Find String
  3. Find Replace
  4. Validate Links
  5. Generate Sitemap

Reference

  1. Go Spec