ch1/ch1-02 #140

2022-11-22T15:55:07Z

giscus[bot]
bot Nov 22, 2022

ch1/ch1-02

中文版

https://gopl-zh.github.io/ch1/ch1-02.html

wlwqq · 2023-01-24T15:59:48Z

wlwqq
Jan 24, 2023 — with giscus

练习1.1 和练习 1.2

for idx, arg := range os.Args {
		if idx == 0 {
			fmt.Println("os.Args[0]=", arg)
		}
		fmt.Println(idx, "=", arg)
}

0 replies

zcg · 2023-03-24T06:00:08Z

zcg
Mar 24, 2023 — with giscus

打卡

0 replies

Sherlockfanchen · 2023-04-14T15:04:43Z

Sherlockfanchen
Apr 14, 2023 — with giscus

package main

import (
"fmt"
"os"
"strings"
"time"
)

func main() {

now := time.Now()
var s, sep string
for i := 1; i < len(os.Args); i++ {
	// timeStamp := now.Unix()
	// fmt.Println(timeStamp)
	s += sep + os.Args[i]
	sep = ""
}
fmt.Println(s)
end := time.Now()
fmt.Println("运行时间", end.Sub(now))

// for index, Args := range os.Args[1:] {
// 	//s += index
// 	fmt.Println(index)
// 	fmt.Println(Args)
// }

now2 := time.Now()
fmt.Println(strings.Join(os.Args[1:], ""))
end2 := time.Now()
fmt.Println("运行时间", end2.Sub(now2))

}

练习3 测试第一个代码块的运行时间是512.5µs 第二个代码块的时间是 507.6µs 可以通过注释来分别运行或者打印fmt.PrintIn(end)和now的时间来看具体的时间

2 replies

Kosthi Jul 28, 2023 — with giscus

练习 1.3

第一种40s，第二种不稳定比40s快一点，第三种在28s左右

测试数据
go run main.go op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf

package main

import (
	"fmt"
	"os"
	"strings"
	time2 "time"
)

func main() {
	var s, sep string

	begin1 := time2.Now()
	for _, arg := range os.Args {
		s += sep + arg
		sep = " "
	}
	fmt.Println(s)
	end1 := time2.Now()
	fmt.Println(end1.Sub(begin1))

	s = ""
	begin2 := time2.Now()
	s += os.Args[0]
	for _, arg := range os.Args[1:] {
		s += " " + arg
	}
	fmt.Println(s)
	end2 := time2.Now()
	fmt.Println(end2.Sub(begin2))

	begin3 := time2.Now()
	fmt.Println(strings.Join(os.Args, " "))
	end3 := time2.Now()
	fmt.Println(end3.Sub(begin3))
}

skyfisher Oct 18, 2024 — with giscus

package main

import (
"fmt"
"os"
"time"
)

func main() {
var s, sep string
var now, end int64
now = time.Now().Local().UnixMicro()

for i := 0; i < len(os.Args); i++ {
	s += sep + os.Args[i]
	sep = " "
	fmt.Print(i)
	fmt.Println(" " + os.Args[i])
}
end = time.Now().Local().UnixMicro()
fmt.Println(s)
fmt.Println(os.Args[0])
fmt.Println(end - now)

}

zb81 · 2023-05-13T10:44:08Z

zb81
May 13, 2023 — with giscus

练习 1.2

for i, v := range os.Args {
	fmt.Printf("%d\t%s\n", i, v)
}

0 replies

Bibooo25730 · 2023-06-14T08:24:08Z

Bibooo25730
Jun 14, 2023 — with giscus

for i := range os.Args {
	fmt.Println(i, "os.Args[0]", os.Args[i])
}

0 replies

haha155200 · 2023-06-14T16:05:49Z

haha155200
Jun 14, 2023 — with giscus

练习1.2
package main

import (
"fmt"
)

func main() {
for i, arg := range "os.Args" {
fmt.Println("第", i, "个", string(arg))

}

0 replies

FPOOOOOOO · 2023-06-29T07:19:33Z

FPOOOOOOO
Jun 29, 2023 — with giscus

echo1、2、3没有输出啊，我的输入是啥呢

1 reply

FPOOOOOOO Jun 29, 2023 — with giscus

我知道了，要从i:=0开始才行，总共就只有1，所以打不出来

package main

import (
	"fmt"
	"os"
)

func main() {
	var s, sep string
	for i := 0; i < len(os.Args); i++ {
		s += sep + os.Args[i]
		sep = " "
	}
	fmt.Println("len = ", len(os.Args))
	fmt.Println(s)
}

SuperZ3 · 2023-07-11T08:15:35Z

SuperZ3
Jul 11, 2023 — with giscus

package main

import (
	"fmt"
	"os"
	"strings"
	"time"
)

func main() {
	s, sep := "", "\r\n"

	now := time.Now()
	for _, arg := range os.Args[:] {
		s += arg + sep
	}
    fmt.Println(s)
	end := time.Now()
	fmt.Println("运行时间", end.Sub(now))

	now2 := time.Now()
	fmt.Println(strings.Join(os.Args[:], "\r\n"))
	end2 := time.Now()
	fmt.Println("运行时间", end2.Sub(now2))
}

// console
/go-build3281070192/b001/exe/hello
a=123
b=456

运行时间 18.984µs
/go-build3281070192/b001/exe/hello
a=123
b=456
运行时间 1.403µs

差了 18 倍？？？

1 reply

Kosthi Jul 28, 2023 — with giscus

好像是有缓存的原因，第二次再处理就很快

junoio · 2023-07-13T05:58:29Z

junoio
Jul 13, 2023 — with giscus

//1.3
func main() {
t := time.Now()
// var s, sep string
// for i := 1; i < len(os.Args); i++ {
// s += sep + os.Args[i]
// sep = " "
// }
// fmt.Println(s)
strings.Join(os.Args[1:], " ")
fmt.Println(time.Since(t).Microseconds())
}

0 replies

Kosthi · 2023-07-28T10:44:56Z

Kosthi
Jul 28, 2023 — with giscus

练习 1.3

第一种40s，第二种不稳定比40s快一点，第三种在28s左右

测试数据
go run main.go op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf

package main

import (
	"fmt"
	"os"
	"strings"
	time2 "time"
)

func main() {
	var s, sep string

	begin1 := time2.Now()
	for _, arg := range os.Args {
		s += sep + arg
		sep = " "
	}
	fmt.Println(s)
	end1 := time2.Now()
	fmt.Println(end1.Sub(begin1))

	s = ""
	begin2 := time2.Now()
	s += os.Args[0]
	for _, arg := range os.Args[1:] {
		s += " " + arg
	}
	fmt.Println(s)
	end2 := time2.Now()
	fmt.Println(end2.Sub(begin2))

	begin3 := time2.Now()
	fmt.Println(strings.Join(os.Args, " "))
	end3 := time2.Now()
	fmt.Println(end3.Sub(begin3))
}

0 replies

Muzych · 2023-08-01T06:17:13Z

Muzych
Aug 1, 2023 — with giscus

练习1.1

fmt.Println(os.Args[0])

练习1.2

import (
  "fmt"
  "os"
  "strconv"
)

func main(){
  var s, sep string
  for idx, args := range os.Args[1:] {
      sep = " "
      s += strconv.Itoa(idx) + sep _+ args
  }
  fmt.Println(s)
}

练习1.3

import (
  "fmt"
  "os"
  "time"
  "strings"
)

func low_func(){
  var s, sep string
  start := time.Now()
  for _, args := range os.Args[1:] {
    s += sep + args
    sep = " "
}
  fmt.Println(s)
  end := time.Now()
  fmt.Println("low running time:", end.Sub(start))
}

func high_func(){
  start := time.Now()
  fmt.Println(strings.Join(os.Args[1:], " "))
  end := time.Now()
  fmt.Println("high running time:", end.Sub(start))
}

func main(){
  low_func()
  high_func()
}

0 replies

longyi-xw · 2023-11-28T03:27:08Z

longyi-xw
Nov 28, 2023 — with giscus

感觉差距不大，测试字符串太少了 74 都波动在504-530微秒以内

func main() {
	forOutput()
	fmt.Println("===========================")
	stringsJoinOut()
}

func forOutput() {
	start := time.Now()
	fmt.Println("1.使用for循环方式打印")
	fmt.Println(os.Args[0])
	var s, sep string
	for i := 1; i < len(os.Args); i++ {
		s += sep + os.Args[i]
		sep = " "
	}
	fmt.Println(s, len(os.Args))
	fmt.Println("运行时间：", time.Since(start).Microseconds())
}

func stringsJoinOut() {
	start := time.Now()
	fmt.Println("2.使用strings.Join打印")
	fmt.Println(os.Args[0])
	fmt.Println(strings.Join(os.Args[1:], " "), len(os.Args))
	fmt.Println("运行时间：", time.Since(start).Microseconds())
}

0 replies

zyz954489346 · 2024-02-21T06:50:26Z

zyz954489346
Feb 21, 2024 — with giscus

strings.Join快的原因是先计算了所有待拼接字符串的总长度，然后一次性分配内存.
而循环拼接则有多次内存开销。
所以后者更快。

0 replies

Aiden-Wang-git · 2024-04-01T07:56:24Z

Aiden-Wang-git
Apr 1, 2024 — with giscus

strings.Join()是一次性分配的地址，所以快很多
func test1() {
args := make([]string, 0, 4)
for i := 0; i < 10000; i++ {
args = append(args, strconv.FormatInt(int64(i), 10))
}
wg := sync.WaitGroup{}
wg.Add(2)
go f1(args, &wg)
go f2(args, &wg)
wg.Wait()
}
func f1(args []string, wg *sync.WaitGroup) {
var s, sep string
now := time.Now()
sep = " "
for i := 1; i < len(args); i++ {
s += sep + args[i]
}
fmt.Printf("%v\n", s)
fmt.Printf("1耗时：%d\n", time.Now().Sub(now).Nanoseconds())
wg.Done()
}
func f2(args []string, wg *sync.WaitGroup) {
now := time.Now()
join := strings.Join(args, " ")
fmt.Printf("%v\n", join)
fmt.Printf("2耗时：%d\n", time.Now().Sub(now).Nanoseconds())
wg.Done()
}

0 replies

zzzk1 · 2024-04-04T06:04:30Z

zzzk1
Apr 4, 2024 — with giscus

for i, arg := range os.Args[1:] {
		println("index: ", i, "value: ", arg)
	}

0 replies

wangdad007 · 2024-04-11T14:40:48Z

wangdad007
Apr 11, 2024 — with giscus

练习1.2

package main

import (
    "fmt"
    "os"
	"strconv"
)

func main() {
    s:=""
	for a,b:=range os.Args[1:]{
		s=strconv.Itoa(a)+" "+b
		fmt.Println(s)
	}
}

0 replies

Fisher0825 · 2024-05-09T09:21:24Z

Fisher0825
May 9, 2024 — with giscus

1.1、1.2
func main() {

for i := 0; i < len(os.Args); i++ {

	fmt.Println(i, os.Args[i])
}

}

0 replies

GaytHub · 2024-06-01T08:47:18Z

GaytHub
Jun 1, 2024 — with giscus

打卡

0 replies

coderZoe · 2024-06-06T07:08:31Z

coderZoe
Jun 6, 2024 — with giscus

练习1

func test1() {
	fmt.Println(strings.Join(os.Args, " "))
}

练习2

func test2() {
	for index, item := range os.Args[1:] {
		fmt.Println(index, item)
	}
}

练习3

func test3() {
	//先构造一个长字符串
	s := os.Args[1:]
	for i := 0; i < 100; i++ {
		s = append(s, s[0])
		s = append(s, s[1])
		s = append(s, s[2])
	}
	start1 := time.Now()

	var result1, step1 string = "", ""
	for _, item := range s {
		result1 += step1 + item
		step1 = ""
	}
	fmt.Println(result1)
	fmt.Printf("time.Now().Sub(start1): %v\n", time.Now().Sub(start1))

	start2 := time.Now()
	result2 := strings.Join(s, " ")
	fmt.Println(result2)
	fmt.Printf("time.Now().Sub(start3): %v\n", time.Now().Sub(start2))

}

0 replies

iotLusian · 2024-07-31T06:59:59Z

iotLusian
Jul 31, 2024 — with giscus

练习1.1

package main

import (
"fmt"
"os"
)

func main() {
fmt.Println(os.Args[0])
}

0 replies

fool-yf · 2024-08-13T05:27:20Z

fool-yf
Aug 13, 2024 — with giscus

// 1.1

func main() {
	fmt.Println(strings.Join(os.Args[0:], " "))
}

// 1.2

func main() {
	for idx, arg := range os.Args {
		fmt.Println(idx, "=", arg)
	}
}

0 replies

yukin371 · 2024-09-21T14:54:04Z

yukin371
Sep 21, 2024 — with giscus

练习···

package main

import (
    "fmt"
    "os"
    "time"
    "strings"
)

func main() {
    var s, sep string
    begin1 := time.Now()
    for index, arg := range os.Args[0:] {
        fmt.Printf("Index: %d, arg: %s\n", index, arg)
    }
    end1 := time.Now()
    fmt.Println("time1:", end1.Sub(begin1))
    
    begin2 := time.Now()
    for _, arg := range os.Args[1:] {
        s += sep + arg
        sep = " "
    }
    fmt.Println(s)
    end2 := time.Now()
    fmt.Println("time2:", end2.Sub(begin2))

    begin3 := time.Now()
    fmt.Println(strings.Join(os.Args[1:], " "))
    end3 := time.Now()
    fmt.Println("time3:", end3.Sub(begin3))
}

用了之前一位仁兄的测试输入，不知道为什么总有0s的
第一次编译：

Index: 0, arg: C:\Users\yukin\AppData\Local\Temp\go-build57938929\b001\exe\package main.exe
Index: 1, arg: op
Index: 2, arg: 81
Index: 3, arg: 213
Index: 4, arg: 19
Index: 5, arg: 0
Index: 6, arg: 12
Index: 7, arg: 90
Index: 8, arg: 66
Index: 9, arg: sidhaifgaifiaf
Index: 10, arg: edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore
Index: 11, arg: 13143ih
Index: 12, arg: 77da
Index: 13, arg: 12131rvf
time1: 0s
op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf
time2: 523.6µs
op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf
time3: 51.4µs

第二次编译

Index: 0, arg: C:\Users\yukin\AppData\Local\Temp\go-build1108872667\b001\exe\package main.exe
Index: 1, arg: op
Index: 2, arg: 81
Index: 3, arg: 213
Index: 4, arg: 19
Index: 5, arg: 0
Index: 6, arg: 12
Index: 7, arg: 90
Index: 8, arg: 66
Index: 9, arg: sidhaifgaifiaf
Index: 10, arg: edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore
Index: 11, arg: 13143ih
Index: 12, arg: 77da
Index: 13, arg: 12131rvf
time1: 3.3041ms
op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf
time2: 0s
op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf
time3: 0s

第三次

Index: 0, arg: C:\Users\yukin\AppData\Local\Temp\go-build2495421148\b001\exe\package main.exe
Index: 1, arg: op
Index: 2, arg: 81
Index: 3, arg: 213
Index: 4, arg: 19
Index: 5, arg: 0
Index: 6, arg: 12
Index: 7, arg: 90
Index: 8, arg: 66
Index: 9, arg: sidhaifgaifiaf
Index: 10, arg: edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore
Index: 11, arg: 13143ih
Index: 12, arg: 77da
Index: 13, arg: 12131rvf
time1: 1.5424ms
op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf
time2: 526.6µs
op 81 213 19 0 12 90 66 sidhaifgaifiaf edadhiuefiauhdiaheuarueabrdabfbaeuiwiajoejqioejoj12iejore 13143ih 77da 12131rvf
time3: 0s

0 replies

fool-yf · 2024-10-23T11:53:33Z

fool-yf
Oct 23, 2024 — with giscus

二刷

0 replies

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ch1/ch1-02 #140

giscus[bot] bot Nov 22, 2022

ch1/ch1-02

Replies: 23 comments · 4 replies

wlwqq Jan 24, 2023 — with giscus

zcg Mar 24, 2023 — with giscus

Sherlockfanchen Apr 14, 2023 — with giscus

Kosthi Jul 28, 2023 — with giscus

skyfisher Oct 18, 2024 — with giscus

zb81 May 13, 2023 — with giscus

Bibooo25730 Jun 14, 2023 — with giscus

haha155200 Jun 14, 2023 — with giscus

FPOOOOOOO Jun 29, 2023 — with giscus

FPOOOOOOO Jun 29, 2023 — with giscus

SuperZ3 Jul 11, 2023 — with giscus

Kosthi Jul 28, 2023 — with giscus

junoio Jul 13, 2023 — with giscus

Kosthi Jul 28, 2023 — with giscus

Muzych Aug 1, 2023 — with giscus

longyi-xw Nov 28, 2023 — with giscus

感觉差距不大，测试字符串太少了 74 都波动在504-530微秒以内

zyz954489346 Feb 21, 2024 — with giscus

Aiden-Wang-git Apr 1, 2024 — with giscus

zzzk1 Apr 4, 2024 — with giscus

wangdad007 Apr 11, 2024 — with giscus

Fisher0825 May 9, 2024 — with giscus

GaytHub Jun 1, 2024 — with giscus

coderZoe Jun 6, 2024 — with giscus

iotLusian Jul 31, 2024 — with giscus

fool-yf Aug 13, 2024 — with giscus

yukin371 Sep 21, 2024 — with giscus

fool-yf Oct 23, 2024 — with giscus

giscus[bot]
bot Nov 22, 2022

Replies: 23 comments 4 replies

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