Constants and Enumerates

Posted on Edited on In Reading time ≈ 1 mins.

Constants

Use keyword const to define constants in Go

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func consts() {
	const (
		filename = "abc.txt"
		path     = "/tmp/"
	)
}

Note, unlike in other languages, consts in Go is not in upper case, since upper case means public in Go.

Enumerate

Enumerate is a special type of const, e.g.

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func enums() {
	const (
		cpp        = 0
		python     = 1
		golang     = 2
		javascript = 3
		java       = 4
	)
	fmt.Println(cpp, python, golang, javascript, java)
}

We could use built-in iota to simplify defining auto-incremental consts

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func enums() {
	const (
		cpp = iota
		python
		golang
		javascript
		java
	)
	fmt.Println(cpp, python, golang, javascript, java)
}

It will print the results:

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0 1 2 3 4

iota can be used in some interesting applications, e.g. enumerate bit, KB, MB etc.

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func enums() {

	const (
		b = 1 << (10 * iota) //left move by 1 digit
		kb
		mb
		gb
		tb
		pb
	)

	fmt.Println(b, kb, mb, gb, tb, pb)
}
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1 1024 1048576 1073741824 1099511627776 1125899906842624