Convert binary File to array of bytes

November 25, 2021

I’m wondering what is the best way to convert binary File to []byte

Here is a sample code that doesn’t work. I’m wondering how I should adjust it to return the content as

func ReadFileAndReturnByteArray(extractedFilePath string) ([]byte, error) {
    file, err := os.Open(extractedFilePath)
    if err != nil {
        return nil, err
    }
    defer file.Close()

    fileinfo, err := file.Stat()
    if err != nil {
        fmt.Println(err)
        return nil, err
    }

    filesize := fileinfo.Size()
    buffer := make([]byte, filesize)

    _, err = file.Read(buffer)
    if err != nil {
        fmt.Println(err)
        return  nil, err
    }
    return buffer, nil
}

>Solution :

The os package provides a ReadFile function which only works for files. It has the exact same signature as your ReadFileAndReturnByteArray function and should be a drop-in replacement.

The io package provides the ReadAll function which works for any io.Reader.

Example:

func ReadFileAndReturnByteArray(extractedFilePath string) ([]byte, error) {
    file, err := os.Open(extractedFilePath)
    if err != nil {
        return nil, err
    }
    defer file.Close()

    return io.ReadAll()
}