To check if a map contains a key in Golang, you can use the form of the index expression v, ok := mainMap[“k”], which returns two elements: a value v of the map with the key k and a boolean value ok equal to true if the key k is present in the map. And then use the if statement to do something based on the value of ok.
Syntax
v, ok := mainMap["k"]
if ok {
// Do something
}
Example
package main
import (
"fmt"
)
func main() {
a := map[string]int{"one": 1, "two": 2}
v, ok := a["one"]
if ok {
fmt.Println(v)
fmt.Println("The map contains a key")
}
v, ok = a["three"]
if !ok {
fmt.Println(v)
fmt.Println("The map does not contain a key")
}
}
Output
1
The map contains a key
0
The map does not contain a key
The v variable will contain the value associated with the key if it exists in the map. If the key does not exist in the map, the v variable will be set to the zero value of the map’s value type (e.g., 0 for an int value).
The ok variable will be a bool that indicates whether the key exists in the map. If ok is true, the key exists in the map; if ok is false, the key does not exist.

Krunal Lathiya is a Software Engineer with over eight years of experience. He has developed a strong foundation in computer science principles and a passion for problem-solving. In addition, Krunal has excellent knowledge of Distributed and cloud computing and is an expert in Go Language.