/* 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)
以下示例说明了如何创建和使用map-
package main
import"fmt"funcmain(){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")}}
Capital of India is New Delhi
Capital of France is Paris
Capital of Italy is Rome
Capital of Japan is Tokyo
Capital of United States is not present
delete()函数
delete()函数用于从map中删除条目。它需要映射和要删除的对应key。例如-
package main
import"fmt"funcmain(){/* 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])}}
Original Map
Capital of France is Paris
Capital of Italy is Rome
Capital of Japan is Tokyo
Capital of India is New Delhi
Entry for France is deleted
Updated Map
Capital of India is New Delhi
Capital of Italy is Rome
Capital of Japan is Tokyo