golang不定長傳參

golang不定長傳參，三個點... 可以很靈活的傳入多個參數，給兩個例子，一看就明白了

1、int類型不定長傳參

package main

import "fmt"

func main() {
    fmt.Println(Sum(1, 4, 6, 7, 8, 9, 100, 200))
}

func Sum(numbers ...int) int {
    result := 0
    for _, n := range numbers {
        result += n
    }
    return result
}

 go run test1.go 
335

2、map類型不定長傳參

package main

import "fmt"

func main() {
    fmt.Println(SumMap(map[string]string{"Italy": "Rome"}, map[string]string{"Japan": "Tokyo"}, map[string]string{"china": "beijing"}))
}

func SumMap(countryCapitalMaps ...map[string]string) map[string]string {
    var result map[string]string
    result = make(map[string]string)
    //注意：這里需要先把多個map的順序取出，否則會報錯
    //cannot use k (type int) as type string in map index
    //cannot use v (type map[string]string) as type string in assignment
    for i, num := range countryCapitalMaps {
        fmt.Println(i)
        fmt.Println(num)
        for k, v := range num {
            result[k] = v
        }
    }
    return result
}

go run test2.go  //這里會打印map的順序號和值
0
map[Italy:Rome]
1
map[Japan:Tokyo]
2
map[china:beijing]
map[Italy:Rome Japan:Tokyo china:beijing]