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@@ -56,6 +56,94 @@ func main() {
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}
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```
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+`inputReader` 是一个指向 `bufio.Reader` 的指针。`inputReader := bufio.NewReader(os.Stdin)` 这行代码，将会创建一个读取器，并将其与标准输入绑定。
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+
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+`bufio.NewReader()` 构造函数的签名为：`func NewReader(rd io.Reader) *Reader`
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+
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+该函数的实参可以是满足 `io.Reader` 接口的任意对象（任意包含有适当的 `Read()` 方法的对象，请参考[章节11.8](11.8.md)），函数返回一个新的带缓冲的 `io.Reader` 对象，它将从指定读取器（例如 `os.Stdin`）读取内容。
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+
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+返回的读取器对象提供一个方法 `ReadString(delim byte)`，该方法从输入中读取内容，直到碰到 `delim` 指定的字符，然后将读取到的内容连同 `delim` 字符一起放到缓冲区。
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+
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+`ReadString` 返回读取到的字符串，如果碰到错误则返回 `nil`。如果它一直读到文件结束，则返回读取到的字符串和 `io.EOF`。如果读取过程中没有碰到 `delim` 字符，将返回错误 `err != nil`。
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+
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+在上面的例子中，我们会读取键盘输入，直到回车键（\n）被按下。
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+
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+屏幕是标准输出 `os.Stdout`；`os.Stderr` 用于显示错误信息，大多数情况下等同于 `os.Stdout`。
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+
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+一般情况下，我们会省略变量声明，而使用 `:=`，例如：
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+```go
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+inputReader := bufio.NewReader(os.Stdin)
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+input, err := inputReader.ReadString('\n')
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+```
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+
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+我们将从现在开始使用这种写法。
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+
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+第二个例子从键盘读取输入，使用了 `switch` 语句：
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+
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+**Listing 12.3—switch_input.go:**
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+
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+```go
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+package main
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+import (
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+ "fmt"
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+ "os"
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+ "bufio"
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+)
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+
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+func main() {
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+ inputReader := bufio.NewReader(os.Stdin)
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+ fmt.Println("Please enter your name:")
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+ input, err := inputReader.ReadString('\n')
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+
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+ if err != nil {
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+ fmt.Println("There were errors reading, exiting program.")
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+ return
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+ }
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+
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+ fmt.Printf("Your name is %s", input)
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+ // For Unix: test with delimiter "\n", for Windows: test with "\r\n"
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+ switch input {
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+ case "Philip\r\n": fmt.Println("Welcome Philip!")
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+ case "Chris\r\n": fmt.Println("Welcome Chris!")
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+ case "Ivo\r\n": fmt.Println("Welcome Ivo!")
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+ default: fmt.Printf("You are not welcome here! Goodbye!")
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+ }
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+
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+ // version 2:
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+ switch input {
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+ case "Philip\r\n": fallthrough
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+ case "Ivo\r\n": fallthrough
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+ case "Chris\r\n": fmt.Printf("Welcome %s\n", input)
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+ default: fmt.Printf("You are not welcome here! Goodbye!\n")
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+ }
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+
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+ // version 3:
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+ switch input {
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+ case "Philip\r\n", "Ivo\r\n": fmt.Printf("Welcome %s\n", input)
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+ default: fmt.Printf("You are not welcome here! Goodbye!\n")
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+ }
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+}
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+```
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+
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+注意：Unix和Windows的行结束符是不同的！
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+
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+**练习**
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+
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+**Exercise 12.1:** word_letter_count.go
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+Write a program which reads text from the keybord. When the user enters ‘S’ in order to signal the end of the input, the program shows 3 numbers:
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+i) the number of characters including spaces (but excluding ‘\r’ and ‘\n’)
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+ii) the number of words
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+iii) the number of lines
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+
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+**Exercise 12.2:** calculator.go
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+Make a simple (reverse polish notation) calculator. This program accepts input from the user in the
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+form of integers (maximum 999999) and operators (+, -, *, /).
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+
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+The input is like this: number1 ENTER number2 ENTER operator ENTER result is displayed.
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+
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+The programs stops if the user inputs “q”. Use the package stack you developed in Ex. 11.3
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+
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+
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## 链接
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- [目录](directory.md)
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Jeff