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Web Technologies - Go Language

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Lesson Description


Lession - #366 Go-Maps


Go - Maps

Go gives another significant information type named map which maps extraordinary keys to values. A key is an article that you use to recover a worth sometime in the future. Given a key and a worth, you can store the worth in a Map object. After the worth is put away, you can recover it by utilizing its key.


/* declare a variable, by default map will be nil*/
var map_variable map[key_data_type]value_data_type

/* define the map as nil map can not be assigned any value*/
map_variable = make(map[key_data_type]value_data_type>


Example

package main

import "fmt"

func main(>
{ var countryCapitalMap map[string]string /* create a map*/ countryCapitalMap = make(map[string]string>
/* insert key-value pairs in the map*/ countryCapitalMap["France"] = "Paris" countryCapitalMap["Italy"] = "Rome" countryCapitalMap["Japan"] = "Tokyo" countryCapitalMap["India"] = "New Delhi" /* print map using keys*/ for country := range countryCapitalMap { fmt.Println("Capital of",country,"is",countryCapitalMap[country]>
} /* test if entry is present in the map or not*/ capital, ok := countryCapitalMap["United States"] /* if ok is true, entry is present otherwise entry is absent*/ if(ok>
{ fmt.Println("Capital of United States is", capital>
} else { fmt.Println("Capital of United States is not present">
} }


delete(>
Function

delete(>
function is utilized to erase a passage from a guide. It requires the guide and the comparing key which is to be erased. For instance −

package main

import "fmt"

func main(>
{ /* create a map*/ countryCapitalMap := map[string] string {"France":"Paris","Italy":"Rome","Japan":"Tokyo","India":"New Delhi"} fmt.Println("Original map">
/* print map */ for country := range countryCapitalMap { fmt.Println("Capital of",country,"is",countryCapitalMap[country]>
} /* delete an entry */ delete(countryCapitalMap,"France">
; fmt.Println("Entry for France is deleted">
fmt.Println("Updated map">
/* print map */ for country := range countryCapitalMap { fmt.Println("Capital of",country,"is",countryCapitalMap[country]>
} }