Essential Go / Maps

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package main import "fmt" func main() { 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)) }
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