Two methods: 1. Use the "for range" statement to traverse the map to obtain all elements, the syntax is "for key, value := range mapName{...}". 2. Use key as an index to obtain the specified element, the syntax is "value, isOk := mapName[key]"; return two return values, the first return value is the obtained value, if the key does not exist, return empty Value, the second parameter is a bool value, indicating whether the value is obtained successfully.

The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.

Two methods to obtain map elements in Go language

Method 1: Use the for range statement to traverse the map to obtain all elements

The traversal of map in Go language can only use the form of for range. The first one returned by the for range loop is the key of the map, and the second one returned is the value of the map.

Syntax:

for key, value := range mapName{
...
}

Description:

• Use for range to loop through the map with the variable name mapName, where key is the key of the map , value is the value corresponding to the key of the map.

Example:

package main
import (
	"fmt"
)
func main() {
	//使用 for range 循環(huán)遍歷 map，獲取 map 的 KEY 和 VALUE
	mapHaiCoder := map[string]string{
		"Server":"Golang",
		"JavaScript":"Vue",
		"Db":"Redis",
	}
	for key, value := range mapHaiCoder{
		fmt.Println("Key =", key, "Value =", value)
	}
}

Method 2: Use key as an index to obtain the specified element

To obtain the elements in the map in the Go language, in addition to using traversal, we can also use key as an index to obtain the elements with the specified key in the map.

Syntax:

value, isOk := mapName[key]

Return value:

Explanation

• Get the elements of the map based on the key of the map and return two return values. One return value is the obtained value. If the key does not exist, a null value is returned. The second parameter is a bool value, indicating whether the obtained value is successful.

Example: Get map elements based on key

Use [] plus key to get map elements

package mainimport (
	"fmt")func main() {
	fmt.Println("嗨客網(wǎng)(www.haicoder.net)")
	//使用 [] 加上 key 的形式，獲取 map 的元素
	mapHaiCoder := map[string]string{
		"Server":"Golang",
		"JavaScript":"Vue",
		"Db":"Redis",
	}
	value, isOk := mapHaiCoder["Server"]
	fmt.Println("Value =", value, "IsOk =", isOk)}

After the program is run, the console output is as follows:

package main
import (
	"fmt"
)
func main() {
	//使用 [] 加上 key 的形式，獲取 map 的元素
	mapHaiCoder := map[string]string{
		"Server":"Golang",
		"JavaScript":"Vue",
		"Db":"Redis",
	}
	value, isOk := mapHaiCoder["Server"]
	fmt.Println("Value =", value, "IsOk =", isOk)
}

We use the initialization method to create a map with three elements, and use the form of [] plus key to obtain The key of the map is the value of the element "Server".

map returns two values. The first is the value corresponding to the key, and the second is a flag indicating whether the key exists. isOk is true, indicating that the key exists.

【Related recommendations: Go video tutorial, Programming teaching】

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