Go: Map: Check for the existence of key in Go

Below snippet is used to check for the existence of key in a map.

if value, ok := map[key]; ok {

    //If key exists in the map, then this code will get executed

} else {

    //If key not exists in the map, then this code will get executed

}

If ‘key’ exists in the map, then the variable ‘ok’ is set to true, and value associated with key is assigned to ‘value’.

If ‘key’ is not exists in the map, then the variable ‘ok’ is set to false, and value is set to ‘zero’ value.

App.go

package main

import "fmt"

func main() {
    employees := make(map[int]string)

    employees[1] = "Krishna"
    employees[2] = "Chamu"
    employees[123] = "Ram"

    key1 := 123

    if value, ok := employees[key1]; ok {
        fmt.Printf("Employee name for the id %v is %v \n", key1, value)
    } else {
        fmt.Printf("Employee with id %v is not exist\n", key1)
    }

    key2 := 125

    if value, ok := employees[key2]; ok {
        fmt.Printf("Employee name for the id %v is %v \n", key2, value)
    } else {
        fmt.Printf("Employee with id %v is not exist\n", key2)
    }
}

Output

Employee name for the id 123 is Ram

Employee with id 125 is not exist

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Go language: Print key, value from map

You can print key, values from a map using for loop.

Example

for key, value := range employees {

         fmt.Println(key, " : ", value)

}

App.java

package main

import "fmt"

func main() {

 employees := map[int]string{
  1: "Krishna",
  2: "Ram",
  3: "Chamu", //Must have trailing comma
 }

 for key, value := range employees {
  fmt.Println(key, " : ", value)
 }
}

Output

1  :  Krishna

2  :  Ram

3  :  Chamu

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Go language: Print all the keys of map

You can print all the keys of a map using for loop.

Example

for key := range employees {

         fmt.Println(key)

}

App.go

package main

import "fmt"

func main() {

 employees := map[int]string{
  1: "Krishna",
  2: "Ram",
  3: "Chamu", //Must have trailing comma
 }

 for key := range employees {
  fmt.Println(key)
 }
}

Output

1

2

3

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