为什么将ReadString（）操作的结果切片会导致奇怪的输出？

Question

package main

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

func main() {
    reader := bufio.NewReader(os.Stdin)

    fmt.Printf("Input: ")
    input, _ := reader.ReadString('
')

    fmt.Println("thing
"[:5] + "\"")
    fmt.Println(input[:len(input)-1] + "\"")

    return
}

Running the code:

Input: thing
thing"
"hing

Why does the second concatenation behave oddly? It should produce identical results, assuming the ReadString() operation returns a string with a newline at the end. Please explain what is going on here.

Answer 1

That's because you're presumably on windows.

The actual input you make from your keyboard is not thing but thing

So when you do fmt.Println(input[:len(input)-1] + "\"") it only truncates the latest and leaves .

So the terminal prints thing, then reaches that returns carriage to the beginning of the string, then you print a double quote. But the carriage is in the first position now, and it effectively overwrites the first character of the line, leaving you with "hing