程序仅输出输入文件的最后一个字符串

Question

i am trying to create a simple program to read lines from a text file and print them out to the console in golang. I spent lots of time going over my code and I simply can't understand why only the last line is being printed out to the screen. can anyone tell me where I am going wrong here? Everything here should compile and run.

package main

import (
    "bufio"
    "fmt"
    "os"
)

func Readln(r *bufio.Reader) (string, error) {
    var (
        isPrefix bool  = true
        err      error = nil
        line, ln []byte
    )
    for isPrefix && err == nil {
        line, isPrefix, err = r.ReadLine()
        ln = append(ln, line...)
    }
    return string(ln), err
}

func main() {
    f, err := os.Open("tickers.txt")
    if err != nil {
        fmt.Printf("error opening file: %v
", err)
        os.Exit(1)
    }
    r := bufio.NewReader(f)
    s, e := Readln(r)
    for e == nil {
        fmt.Println(s)
        s, e = Readln(r)
    }
}

Answer 1

I therefore suspect that the problem is in your tickers.txt file line endings. The docs for ReadLine() also indicate that for most situations a Scanner is more suitable.

The following SO question has some useful information for alternative implementations: reading file line by line in go

I then used the example in the above question to re-implement your main function as follows:

f, err := os.Open("tickers.txt")
if err != nil {
    fmt.Printf("error opening file: %v
", err)
    os.Exit(1)
}

scanner := bufio.NewScanner(f)
for scanner.Scan() {
    fmt.Println(scanner.Text())
}

if err := scanner.Err(); err != nil {
    fmt.Println(err)
}