golang 参数传递

array.go

package main

import (
	"log"
)

func main() {
	i := [...]int{1, 2, 3}
	log.Printf("before show: %v", i)
	show(i)
	log.Printf("after show: %v", i)
}

func show(i [3]int) {
	i[0]++
	log.Printf("in show: %v", i)
}

// 2018/09/18 10:57:28 before show: [1 2 3]
// 2018/09/18 10:57:28 in show: [2 2 3]
// 2018/09/18 10:57:28 after show: [1 2 3]

array_ptr.go

package main

import (
	"log"
)

func main() {
	i := &[...]byte{1, 2, 3}
	log.Printf("before show: %v", i)
	show(i)
	log.Printf("after show: %v", i)
}

func show(i *[3]byte) {
	i[0]++
	log.Printf("in show: %v", i)
}

// 2018/09/18 11:12:46 before show: &[1 2 3]
// 2018/09/18 11:12:46 in show: &[2 2 3]
// 2018/09/18 11:12:46 after show: &[2 2 3]

map.go

package main

import (
	"log"
)

func main() {
	i := map[string]int{"a": 1, "b": 2}
	log.Printf("before show: %v", i)
	show(i)
	log.Printf("after show: %v", i)
}

func show(i map[string]int) {
	i["a"]++
	log.Printf("in show: %v", i)
}

// 2018/09/18 11:01:30 before show: map[a:1 b:2]
// 2018/09/18 11:01:30 in show: map[a:2 b:2]
// 2018/09/18 11:01:30 after show: map[a:2 b:2]

slice.go

package main

import (
	"log"
)

func main() {
	i := []int{1, 2, 3}
	log.Printf("before show: %v", i)
	show(i)
	log.Printf("after show: %v", i)
}

func show(i []int) {
	i[0]++
	log.Printf("in show: %v", i)
}

// 2018/09/18 10:57:28 before show: [1 2 3]
// 2018/09/18 10:57:28 in show: [2 2 3]
// 2018/09/18 10:57:28 after show: [2 2 3]

struct.go

package main

import (
	"log"
)

type test struct {
	Name  string
	Value int
}

func main() {
	i := test{"a", 1}
	log.Printf("before show: %v", i)
	show(i)
	log.Printf("after show: %v", i)
}

func show(i test) {
	i.Value++
	log.Printf("in show: %v", i)
}

// 2018/09/18 11:03:46 before show: {a 1}
// 2018/09/18 11:03:46 in show: {a 2}
// 2018/09/18 11:03:46 after show: {a 1}

struct_ptr.go

package main

import (
	"log"
)

type test struct {
	Name  string
	Value int
}

func main() {
	i := &test{"a", 1}
	log.Printf("before show: %v", i)
	show(i)
	log.Printf("after show: %v", i)
}

func show(i *test) {
	i.Value++
	log.Printf("in show: %v", i)
}

// 2018/09/18 11:04:59 before show: &{a 1}
// 2018/09/18 11:04:59 in show: &{a 2}
// 2018/09/18 11:04:59 after show: &{a 2}

summary.md

值类型

• int float string 不可寻址 复制值
• array struct 复制值

引用类型

• map slice chan 复制引用

指针类型

• *array *struct 复制指针