dongrui6787
dongrui6787
2016-03-30 07:31

Golang将字符串转换为io.Writer?

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Is it possible to convert a string to an io.Writer type in Golang?

I will be using this string in fmt.Fprintf() but I am unable to convert the type.

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2条回答

  • dongpu42006096 dongpu42006096 5年前

    You can't write into a string, strings in Go are immutable.

    The best alternatives are the bytes.Buffer and since Go 1.10 the faster strings.Builder types: they implement io.Writer so you can write into them, and you can obtain their content as a string with Buffer.String() and Builder.String(), or as a byte slice with Buffer.Bytes().

    You can also have a string as the initial content of the buffer if you create the buffer with bytes.NewBufferString():

    s := "Hello"
    buf := bytes.NewBufferString(s)
    fmt.Fprint(buf, ", World!")
    fmt.Println(buf.String())
    

    Output (try it on the Go Playground):

    Hello, World!
    

    If you want to append a variable of type string (or any value of string type), you can simply use Buffer.WriteString() (or Builder.WriteString()):

    s2 := "to be appended"
    buf.WriteString(s2)
    

    Or:

    fmt.Fprint(buf, s2)
    

    Also note that if you just want to concatenate 2 strings, you don't need to create a buffer and use fmt.Fprintf(), you can simply use the + operator to concatenate them:

    s := "Hello"
    s2 := ", World!"
    
    s3 := s + s2  // "Hello, World!"
    

    Also see: Golang: format a string without printing?

    It may also be of interest: What's the difference between ResponseWriter.Write and io.WriteString?

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  • douqian8238 douqian8238 2年前

    Use bytes.Buffer which implements the Write() method.

    import "bytes"
    
    writer := bytes.NewBufferString("your string")
    
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