Problems with array slicing reliability?

[Mucas Schlack]

Hello Golangers!

Is there anyone who can test the reliability of the following Golang slice feature? I am using an AMG64 computer with Windows 10, and Go version 0.36.0. When I use the following code, to detect and then replace a character at any given length n (9) in a string with an Uppercase Character. Strangely and somehow, the slice pointer will move to another position even though the code is not dynamic and has not changed. Is there anyone who can trouble shoot this code for me?

Please remember that this is "test" code only, so some of it will not make any sense or work. It is only "proof of concept" code.

The code to pay attention to is the following - from lines: 80 - 92!

Many thanks for any help you can give!

Mucas

Example code:

package main

import(

    //"unicode/utf8"

    "math/rand"

    "strconv"

    "strings"

    "fmt"

    "time"

    "os"

)

var alphanumerics = [62] string {

    "a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z",

    "0","1","2","3","4","5","6","7","8","9",

    "A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z",

    }

func main(){

var (

        txtflpth string = "C:\\Workspace\\Transaction Hash.txt"

        flNm string = "Transaction Hash.txt"

        CRLF string = "\n"

        cntstrt string

        AuthKey string

        NwStr string

        cstart int

        cntr int

        flEx *os.FileInfo

        flEx2 *os.File

        trfl *os.File

        err error

    )

    fmt.Print("State where the hash counter should begin:>> ")

    fmt.Scanln(&cntstrt)

    if cntstrt == "" || cntstrt == " " {    

        trfl, err = os.Create(flNm)

       

        if err != nil { panic(err); os.Exit(-1) }

        defer trfl.Close()

    } else {

        var flEx, err = os.Stat(txtflpth)

       

        fmt.Println(flEx.Mode().String)

        //fmt.Println(flEx.IsRegular())

        fmt.Println(flEx.IsDir())

        fmt.Println(flEx.Name())

        fmt.Println(flEx.Size())

        fmt.Println(flEx.Sys())

        if err != nil { if os.IsNotExist(err) { panic(err) } }

       

        cstart, err = strconv.Atoi(cntstrt)

        flEx2, err := os.Open(txtflpth)

        defer flEx2.Close()

    }

    /*defer func(

        if err == trfl.Close() || err == os.IsNotExist(err)!= err { panic(err) }

        if err == flEx.Close() || err == os.IsNotExist(err)!= err { panic(err) }

    )*/

    if cntstrt != "" && cntstrt != " " { cntr = cstart }

    for cntr = cstart; cntr < cstart + 1000; cntr++ {

        NwStr = ""

        AuthKey = NwStr

        for i := 0; i <= 65; i++ {

            time.Sleep(10 * time.Nanosecond)

            rand.Seed(time.Now().UnixNano())

            AuthKey = AuthKey + alphanumerics[rand.Intn(62)] //, [A - Z], [0-9])

        }

        var hashRemap = [...] string {"A","U","G","D","E","X"}

       

        AuthKey = "0x" + AuthKey

        fmt.Println("Transaction Hash: " + strconv.Itoa(cntr) + ") " + AuthKey)

        //AuthKey2 := []rune(AuthKey)

        StrPos := strings.Index(AuthKey, AuthKey[9:10])

        fmt.Printf("The old character %s is at string position: (%d) " + CRLF,AuthKey[9:10], StrPos)

        //os.Exit(1)

        for i := 0; i < 6; i++ {

            switch i {

                case 0: AuthKey = strings.Replace(AuthKey,AuthKey[9:10], hashRemap[0], 1); fmt.Println("Replaced! The New Transaction Hash: " + "(" + strconv.Itoa(i) + ") " + AuthKey); os.Exit(1);

                case 1: AuthKey = strings.Replace(AuthKey,"", hashRemap[1], 1)

                case 2: AuthKey = strings.Replace(AuthKey,"", hashRemap[3], 1)

                case 3: AuthKey = strings.Replace(AuthKey,"", hashRemap[4], 1)

                case 4: AuthKey = strings.Replace(AuthKey,"", hashRemap[5], 1)

                case 5: AuthKey = strings.Replace(AuthKey,"", hashRemap[5], 1)

            }

           

        }

        fmt.Println("Transaction Hash: " + strconv.Itoa(cntr) + ") " + AuthKey)

        if trfl != nil { trfl.WriteString("Transaction Hash: " + strconv.Itoa(cntr) + ") " + AuthKey + CRLF) }

        if flEx != nil { flEx2.WriteString("Transaction Hash: " + strconv.Itoa(cntr) + ") " + AuthKey + CRLF) }

[Nikhilesh Susarla]

Before anyone takes a look, can you please place the code in https://go.dev/play/ and then share that link where the code compiles and if it works on the browser and you have specific settings for goarch and goos then gophers can take a look at it. 

Thank you

[Kurtis Rader]

You cannot mutate strings. Your code is also missing a final close-brace and possibly has other problems. That your example includes commented out code is also problematic. As Nikhilesh Susarla pointed out you should post a link to the Go playground to avoid any ambiguity.

I added the missing close-brace to your code and observed the following behavior (I entered "1" at the prompt):

> go run x.go                                                              144.6 ms

State where the hash counter should begin:>> 1

panic: runtime error: invalid memory address or nil pointer dereference

[signal SIGSEGV: segmentation violation code=0x2 addr=0x28 pc=0x102536674]

This tells me there is a fundamental bug in your code having nothing to do with "Problems with array slicing reliability"

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Kurtis Rader

Caretaker of the exceptional canines Junior and Hank

[Amnon]

As others have said, it is worth trying to reduce the program to the minimal version which reproduces your problem
(and then publishing it on https://go.dev/play/ ).

[TheDiveO]

On Wednesday, November 23, 2022 at 10:57:03 PM UTC+1 loji...@gmail.com wrote:

[...] I am using an AMG64 computer with Windows 10, and Go version 0.36.0. [emphasis mine]

 

Go version 0.36.0? Really?