iota

iotaIt is a constant counter in go language and can only be used in constant expressions.

iotaWill be reset to 0 when the const keyword is present. Each new line of constant declaration in const will iotacount once (iota can be understood as the line index in the const statement block). Using iota simplifies the definition and is useful when defining enumerations.

for example:

const (
		n1 = iota //0
		n2        //1
		n3        //2
		n4        //3
	)

A few common iotaexamples:

Use _skip certain values

const (
		n1 = iota //0
		n2        //1
		_
		n4        //3
	)

iotaStatement cut in the middle

const (
		n1 = iota //0
		n2 = 100  //100
		n3 = iota //2
		n4        //3
	)
	const n5 = iota //0

Define the order of magnitude (the <<left shift operation here means 1<<10that the binary representation of 1 is shifted to the left by 10 bits, that is, it 1becomes 100000000001024 in decimal. Similarly, 2<<2it means that the binary representation of 2 is shifted to the left by 2 bits, also It is 10changed from to 1000, which is 8 in decimal.)

const (
		_  = iota
		KB = 1 << (10 * iota)
		MB = 1 << (10 * iota)
		GB = 1 << (10 * iota)
		TB = 1 << (10 * iota)
		PB = 1 << (10 * iota)
	)

Multiple iotadefinitions on one line

const (
		a, b = iota + 1, iota + 2 //1,2
		c, d                      //2,3
		e, f                      //3,4
	)