如何在映射中区分空字符串和什么都没有[重复]

Question

This question already has an answer here:

• How to check if a map contains a key in Go? 9 answers

The following code yields true. So I'm wondering for map[string]string in Golang, is there a way to differentiate empty string and nothing?

package main

import "fmt"

func main() {
    m := make(map[string]string)
    m["abc"] = ""
    fmt.Println(m["a"] == m["abc"]) //true
}

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Answer 1

If by "nothing" you mean that the element is not in the map you can use the ok idiom:

val, ok := myMap["value"] // ok is true if value was in the map

You can find more information in Effective Go.