Iterating over all the keys of a map

user_30541 0
Viewed 353758

Is there a way to get a list of all the keys in a Go language map? The number of elements is given by len(), but if I have a map like:

m := map[string]string{ "key1":"val1", "key2":"val2" };

How do I iterate over all the keys?

go dictionary loops
6 Answers

A Type agnostic solution:

for _, key := range reflect.ValueOf(yourMap).MapKeys() {
    value := yourMap.MapIndex(key).Interface()
    fmt.Println("Key:", key, "Value:", value)
}
user_5143290

Using Generics:

func Keys[K comparable, V any](m map[K]V) []K {
    keys := make([]K, 0, len(m))

    for k := range m {
        keys = append(keys, k)
    }

    return keys
}
user_14194800

For sorted keys of map[string]string.

package main

import (
    "fmt"
    "sort"
)

func main() {
    m := map[string]string{"key1": "val1", "key2": "val2"}
    sortStringMap(m)
}

// sortStringMap prints the [string]string as keys sorted
func sortStringMap(m map[string]string) {
    var keys []string
    for key := range m {
        keys = append(keys, key)
    }
    sort.Strings(keys)  // sort the keys
    for _, key := range keys {
        fmt.Printf("%s\t:%s\n", key, m[key])
    }
}

output:

key1    :val1
key2    :val2
user_121938180
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