Skip to content

Instantly share code, notes, and snippets.

@kjk
Created Nov 5, 2019
Embed
What would you like to do?
Maps
// :collection Essential Go
package main
import "fmt"
func main() {
// :show start
m := make(map[string]int)
// set the value
m["three"] = 3
m["four"] = 4
// get the value and see if the value exists
key := "four"
if value, ok := m[key]; ok {
fmt.Printf("Key '%s' exists and maps to %d\n", key, value)
} else {
fmt.Printf("Key '%s' doesn't exists\n", key)
}
key = "five"
if value, ok := m[key]; ok {
fmt.Printf("Key '%s' exists and maps to %d\n", key, value)
} else {
fmt.Printf("Key '%s' doesn't exists\n", key)
}
// if value doesn't exist, the result of lookup is zero value. In this case zero value of int is 0
fmt.Printf("\nValue for non-existing key: %d\n\n", m["not-exists"])
// iterating over keys and values
fmt.Printf("All keys and their values:\n")
for key, value := range m {
fmt.Printf("%s => %d\n", key, value)
}
fmt.Printf("\nBefore deletion: len(m)=%d\n", len(m))
delete(m, "four")
fmt.Printf("After deletion : len(m)=%d\n", len(m))
// :show end
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment