How to Merge Maps in Golang

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To merge the maps in Golang, you can use the “for loop” to traverse over one map and append its key-value pairs to the second map. 

package main

import (
  "fmt"
)

func main() {
  map1 := map[string]int{
    "bdy_kl": 10,
    "eno_kl": 21,
 }
  map2 := map[string]int{
    "bdy_kb": 20,
    "eno_kb": 19,
 }

  // Print the map before merging
  fmt.Println("The First Map: ", map1)
  fmt.Println("The Second Map: ", map2)

  for x, y := range map1 {
    map2[x] = y
  }
  fmt.Println("The merged Map is: ", map2)
}

Output

The First Map: map[bday_kl:10 eno_kl:21]
The Second Map: map[bday_kb:20 eno_kb:19]
The merged Map is: map[bday_kb:20 bday_kl:10 eno_kb:19 eno_kl:21]

In this example, we created two maps with four different key: value pairs. 

Used the Prinln() function to print the maps.

Using for loop and range, we are traversing map1 and appending map1’s key: value pair to map2 and return the merged maps.

The approach will overwrite any key-value pairs in map2 that have the same keys as those in map1. If you want to preserve the values in map2, you can check for the presence of a key in the map before adding it.

To append a new key-value pair to a map, use the syntax map[key] = value.

You must be careful while using the approach because If a key already has a value, that value will be obliterated.

That’s it for this article.

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