Golang對逆波蘭表示法的簡單實現

 1 package main
 2 import (
 3     "bufio"
 4     "fmt"
 5     "os"
 6     "strconv"
 7 )
 8 type Stack struct {
 9     i int
10     data [10]int
11 }
12 func (s *Stack) Push(a int) {
13     fmt.Printf("push:data:%d,pos:%d\n", a, s.i)
14     s.data[s.i] = a
15     s.i++
16 }
17 func (s *Stack) Pop() int {
18     s.i--
19     return s.data[s.i]
20 }
21 
22 var reader *bufio.Reader = bufio.NewReader(os.Stdin)
23 var st Stack
24 func main() {
25     for {
26         s, err := reader.ReadString('\n')
27         var token string
28         if err != nil {
29             println("Good Bye!")
30             continue
31         }
32         for _, c := range s {
33             switch {
34             case c >= '0' && c <= '9':
35                 token += string(c)
36             case c == ' ':    // 一個數輸入結束
37                 if token != "" {
38                     r, _ := strconv.Atoi(token)
39                     st.Push(r)
40                     token = ""
41                 }
42             case c == '+':
43                 st.Push(st.Pop() + st.Pop())
44             case c == '*':
45                 st.Push(st.Pop() * st.Pop())
46             case c == '-':
47                 p := st.Pop()
48                 q := st.Pop()
49                 st.Push(q-p)
50             case c == '/':
51                 p := st.Pop()
52                 q := st.Pop()
53                 if p != 0 {
54                     st.Push(q/p)
55                 } else {
56                     fmt.Printf("divisor couldn't be zero\n")
57                 }
58             case c == '\n':
59                 fmt.Printf("%d\n",st.Pop());
60             case c == 'q':
61                 return
62             
63             }
64         }
65     }
66 }