Go中的文本处理-如何将字符串转换为字节？

Question

I'm writing a small pragram to number the paragraph:

1. put paragraph number in front of each paragraph in the form of [1]..., [2]....
2. Article title should be excluded.

Here is my program:

package main

import (
    "fmt"
    "io/ioutil"
)

var s_end = [3]string{".", "!", "?"}

func main() {
    b, err := ioutil.ReadFile("i_have_a_dream.txt")
    if err != nil {
        panic(err)
    }

    p_num, s_num := 1, 1

    for _, char := range b {
        fmt.Printf("[%s]", p_num)
        p_num += 1
        if char == byte("
") {
            fmt.Printf("
[%s]", p_num)
            p_num += 1
        } else {
            fmt.Printf(char)
        }
    }
}

http://play.golang.org/p/f4S3vQbglY

I got this error:

prog.go:21: cannot convert "
" to type byte
prog.go:21: cannot convert "
" (type string) to type byte
prog.go:21: invalid operation: char == "
" (mismatched types byte and string)
prog.go:25: cannot use char (type byte) as type string in argument to fmt.Printf
[process exited with non-zero status]

How to convert string to byte?

What is the general practice to process text? Read in, parse it by byte, or by line?

Update

I solved the problem by converting the buffer byte to string, replacing strings by regular expression. (Thanks to @Tomasz Kłak for the regexp help)

I put the code here for reference.

package main

import (
    "fmt"
    "io/ioutil"
    "regexp"
)


func main() {
    b, err := ioutil.ReadFile("i_have_a_dream.txt")
    if err != nil {
        panic(err)
    }

    s := string(b)
    r := regexp.MustCompile("(
)+")
    counter := 1

    repl := func(match string) string {
        p_num := counter
        counter++
        return fmt.Sprintf("%s [%d] ", match, p_num)
    }

    fmt.Println(r.ReplaceAllStringFunc(s, repl))
}

Answer 1

Using " " causes it to be treated as an array, use ' ' to treat it as a single char.