05-constant.go

/*
 * @Author: Barnabas Makonda
 * @Date: 2019-01-11 15:52:36
 * @Last Modified by: Barnabas Makonda
 * @Last Modified time: 2019-01-11 16:23:36
 */

package main

import "fmt"

/*
 * Constant is an expression that is know during compile time.
 * It hold value that was declared and assigned to it all tne time as long as program is running.
 * The type is inferred from the right hand side of the expression.
 *
 *
 */

func main() {
	// You can assign single constant a value. Type is inferred from the right side.
	// For this case compiler see "John" as string and hence name become of type string.
	const name = "John"

	// You can create multiple constants at once
	const (
		numberOne = 1
		msg       = "Jambo"
	)

	/* iota can be used to generate set of related constant but distict. can be used to represent
	 * property that has several distinct possible values. Eg. Days of the week, Month of the years
	 * They are like enumerated(enum)type from other language.
	 */

	type DaysOfTheWeek int
	type Grades int

	// you will only have to specify type once for constants and the rest will be assigned
	// unique value with the same datatype as the one assigned to the first one.

	const (
		Monday DaysOfTheWeek = iota
		Tuesday
		Wednesday
		Thursday
		Friday
	)

	const (
		A Grades = iota
		B
		C
		D
		E
		F
	)

	fmt.Println(name, numberOne, msg)
	fmt.Println(Monday, Tuesday, Wednesday, Thursday, Friday)
	fmt.Println(A, B, C, D, E, F)

}