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Kenta Takeuchi
Kenta Takeuchi

Posted on • Originally published at bmf-tech.com

Summary of Variable Definitions and Declarations in Golang

#go

This article was originally published on bmf-tech.com.

Overview

A summary of patterns for variable definitions and declarations in Golang.

Cautions in Variable Definitions and Declarations

  • If the first letter is uppercase, the variable is visible from other packages.
  • If the first letter is lowercase, the variable is only visible within the package.

Variable Definitions and Declarations

Variable declarations 

var i int
fmt.Printf("%T", i) // int
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var a, b, c string
fmt.Printf("%T", a) // string
fmt.Printf("%T", b) // string
fmt.Printf("%T", c) // string
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var s = "Hello World"
fmt.Printf("%T", s) // string
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var x, y, z int = 1, 2, 3
fmt.Printf("%T", x) // int
fmt.Printf("%T", y) // int
fmt.Printf("%T", z) // int
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var (
   a string
   x int
   y, z = 2, 3
)
fmt.Printf("%T", a) // string
fmt.Printf("%T", x) // int
fmt.Printf("%T", y) // int
fmt.Printf("%T", z) // int
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var i, j = 1, 2
fmt.Printf("%T", i) // int
fmt.Printf("%T", j) // int
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Short variable declarations

  • The shorthand variable declaration can only be used within functions. 
i := 1
fmt.Printf("%T", i) // int
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i, j := 1, 2
fmt.Printf("%T", i) // int
fmt.Printf("%T", j) // int
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References

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