can't open file if its name was read from stdin

[buzze...@gmail.com]

Does anyone know why Google Go program 1 works, below, and program 2 doesn't? The only difference - I read in the filename from the console in the one that doesn't work but it is a literal in the one that works... I tried typing in the full path for the file, and also "..sample.txt" instead of "sample.txt", but they didn't solve it either.

// program 1 - this works:

    package main import (

            "fmt"

            "os"

            "bufio" )

        

        func main() {

            filename := getFilename()

        fmt.Println("opening:",filename) 

    //      fmt.Println("opening:sample.txt")

            _ , err := os.Open("sample.txt") 

    //   _ , err := os.Open(filename)

            if err != nil { 

        panic(err)

            } 

        } 

    func getFilename()  string {

        reader := bufio.NewReader(os.Stdin)

        fmt.Print("Enter file name: ")    // type in anything, this file name not used

        filename, _ := reader.ReadString('\n')

        return filename

    }

// program 2 - this doesn't work, gives error shown below:

    package main

    import (

        "fmt"

        "os"

        "bufio"

    )

    

    func main() 

        filename := getFilename()

        fmt.Println("opening:",filename)

    // fmt.Println("opening: sample.txt")

    // _ , err := os.Open("sample.txt")

        _ , err := os.Open(filename)

        if err != nil {

        panic(err)

        }

        }

    func getFilename()  string {

        reader := bufio.NewReader(os.Stdin)

        fmt.Print("Enter file name: ")    // type in "sample.txt" (without the quotes)

        filename, _ := reader.ReadString('\n')

        return filename

    }

Error message, panic invoked - 

: The filename, directory name, or volume label syntax is incorrect.

goroutine 1 [running]:

main.main()

        C:/installed programs/go/src/testopen2.go:16 +0x158

exit status 2

[Dave Cheney]

Check the error from ReadString to find out why it's returning a empty string.

[Uli Kunitz]

ReadString returns the line including the terminating newline ('\n'). You can check it with fmt.Printf("filename: %q\n", filename). One option to fix it is using function strings.TrimSpace. It will remove all space characters at the start and the end of the string. 

[Geoff Fridd]

I found the solution myself - when read in from stdin, there are 2 extra characters - CR and LF.  I just cut the string 2 characters before the end, and it works!  Thanks to those for posting replies!

[Uli Kunitz]

Good, that you found the problem yourself. I wasn't aware that you were on Windows were newlines are represented by CRLF ("\r\n"). TrimSpace would deal with that as well.