Golang 面试题-Toy模板网

这篇具有很好参考价值的文章主要介绍了Golang 面试题。希望对大家有所帮助。如果存在错误或未考虑完全的地方，请大家不吝赐教，您也可以点击"举报违法"按钮提交疑问。

golang 面试题 - 诺唯的文章 - 知乎
https://zhuanlan.zhihu.com/p/26972862

Panic and defer

package main

import (
   "fmt"
)

func main() {
   defer_call()
}

func defer_call() {
   defer func() { fmt.Println("打印前") }()
   defer func() { fmt.Println("打印中") }()
   defer func() { fmt.Println("打印后") }()

   panic("触发异常")
}

panic 触发会停止函数运行，然后按照栈的顺序执行 defer，最后退出函数，终止整个程序
2. map

 package main

import "fmt"

type student struct {
	Name string
	Age  int
}

func pase_student() {
	m := make(map[string]*student)
	stus := []student{
		{Name: "zhou", Age: 24},
		{Name: "li", Age: 23},
		{Name: "wang", Age: 22},
	}
	for _, stu := range stus {
		m[stu.Name] = &stu
	}
	fmt.Println(m)
}

func main() {
	pase_student()
	fmt.Println("Hello, 世界")
}

map[li:0xc000010030 wang:0xc000010030 zhou:0xc000010030]
Hello, 世界

stu 仅仅是一个用来拷贝的 struct, 取地址不变，可改为索引取值
3. goroutine

package main

import (
	"fmt"
	"runtime"
	"sync"
)

func main() {
	runtime.GOMAXPROCS(1)
	wg := sync.WaitGroup{}
	wg.Add(20)
	for i := 0; i < 10; i++ {
		go func() {
			fmt.Println("i: ", i)
			wg.Done()
		}()
	}
	for i := 0; i < 10; i++ {
		go func(i int) {
			fmt.Println("i: ", i)
			wg.Done()
		}(i)
	}
	wg.Wait()
}

i: 9
i: 10
i: 10
i: 10
i: 10
i: 10
i: 10
i: 10
i: 10
i: 10
i: 10
i: 0
i: 1
i: 2
i: 3
i: 4
i: 5
i: 6
i: 7
i: 8

不传参的话用的永远都是一个 i
4.

package main

import (
	"fmt"
)

type People struct{}

func (p *People) ShowA() {
	fmt.Println("showA")
	p.ShowB()
}
func (p *People) ShowB() {
	fmt.Println("showB")
}

type Teacher struct {
	People
}

func (t *Teacher) ShowB() {
	fmt.Println("teacher showB")
}

func main() {
	t := Teacher{}
	t.ShowA()
}

showA
showB

select 语句

package main

import (
	"fmt"
	"runtime"
)

func main() {
	runtime.GOMAXPROCS(1)
	int_chan := make(chan int, 1)
	string_chan := make(chan string, 1)
	int_chan <- 1
	string_chan <- "hello"
	select {
	case value := <-int_chan:
		fmt.Println(value)
	case value := <-string_chan:
		panic(value)
	}
}

随机情况，多个 case 满足程序会伪随机执行一个
6. defer order

import (
	"fmt"
)

func calc(index string, a, b int) int {
	ret := a + b
	fmt.Println(index, a, b, ret)
	return ret
}

func main() {
	a := 1
	b := 2
	defer calc("1", a, calc("10", a, b))
	a = 0
	defer calc("2", a, calc("20", a, b))
	b = 1
}

10 1 2 3
20 0 2 2
2 0 2 2
1 1 3 4

先执行函数参数，defer 按照栈序执行
7.

func main() {
	s := make([]int, 5)
	s = append(s, 1, 2, 3)
	fmt.Println(s)
}

[0 0 0 0 0 1 2 3]
make 已经初始化结果

8.map

package main

import (
	"fmt"
	"sync"
)

type UserAges struct {
	ages map[string]int
	sync.Mutex
}

func (ua *UserAges) Add(name string, age int) {
	ua.Lock()
	defer ua.Unlock()
	ua.ages[name] = age
}

func (ua *UserAges) Get(name string) int {
	if age, ok := ua.ages[name]; ok {
		return age
	}
	return -1
}
func main() {
	s := make([]int, 5)
	s = append(s, 1, 2, 3)
	fmt.Println(s)
}

可能对 map 同时读写造成 panic
9.channel

func (set *threadSafeSet) Iter() <-chan interface{} {
	ch := make(chan interface{})
	go func() {
		set.RLock()

		for elem := range set.s {
			ch <- elem
		}

		close(ch)
		set.RUnlock()

	}()
	return ch
}

无缓冲的 channel 会发送阻塞，知道接收出数据
10.

package main

import (
	"fmt"
)

type People interface {
	Speak(string) string
}

type Stduent struct{}

func (stu *Stduent) Speak(think string) (talk string) {
	if think == "bitch" {
		talk = "You are a good boy"
	} else {
		talk = "hi"
	}
	return
}

func main() {
	var peo People = Stduent{}
	think := "bitch"
	fmt.Println(peo.Speak(think))
}

出错，指针和值的成员方法调用不一致
11.nil check

package main

import (
	"fmt"
)

type People interface {
	Show()
}

type Student struct{}

func (stu *Student) Show() {

}

func live() People {
	var stu *Student
	fmt.Println(stu)
	return stu
}

func main() {

	if live() == nil {
		fmt.Println("AAAAAAA")
	} else {
		fmt.Println("BBBBBBB")
	}
	a := live()
	if v, ok := a.(*Student); ok {
		fmt.Println(v == nil)

	}
}