golang rsa密鑰

When you try to get the value of key in a map, you get two return values. The first value is the value of key and second is bool value which could be either true or false. If a key is present in the map then the second value will be true else false.

當(dāng)您嘗試獲取映射中的key值時，您將獲得兩個返回值。 第一個值是key的值，第二個值是bool值，可以為true或false。 如果映射中存在鍵，則第二個值將為true，否則為false 。

If a key is not present in the map then the first value will be default zero value.

如果映射中不存在鍵，則第一個值為默認(rèn)的零值。

Syntax:

句法：

first_value, second_value := map_variable_name[key_name]orfirst_value := map_variable_name[key_name]orfirst_value, _ := map_variable_name[key_name]

Here, second_value is optional.

在這里， second_value是可選的。

Code example:

代碼示例：

package mainimport ("fmt" )func main() {m:= map[string]int{"apple": 1}value, ok := m["apple"]fmt.Println(value, ok)value, ok = m["mango"]fmt.Println(value, ok) }

Output

輸出量

1 true 0 false

Check key exists in map using if-statement

使用if語句在地圖中檢查密鑰是否存在

package mainimport ("fmt" )func main() {m:= map[string]int{"apple": 1}if value, ok := m["apple"]; ok {fmt.Printf("Apple is present in map. Value is: %d\n", value)} else {fmt.Printf("Apple is not present in map. Value is: %d\n", value)}if value, ok := m["mango"]; ok {fmt.Printf("Mango is present in map. Value is: %d\n", value)} else {fmt.Printf("Mango is not present in map. Value is: %d\n", value)} }

Output

輸出量

Apple is present in map. Value is: 1 Mango is not present in map. Value is: 0

翻譯自: https://www.includehelp.com/golang/how-to-check-if-key-exists-in-a-map-in-golang.aspx

golang rsa密鑰

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