如何在Golang中检查地图是否为空？

Question

I've tried

if map == nil {
    log.Fatal("map is empty")
}

But the log statement is not executed.

I used fmt.Println(map) to print the map, and one can see it's empty:

map[]

How do I test for an empty map?

Answer 1

You can use len:

if len(map) == 0 {
    ....
}

From https://golang.org/ref/spec#Length_and_capacity

len(s) map[K]T map length (number of defined keys)