8. 字符串转换整数 (atoi)

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这道主要是需要考虑这个bad case

  1. package main
  3. import (
  4.     "math"
  5.     "fmt"
  6.     "strings"
  7. )
  9. func myAtoi(str string) int {
  10.     //去掉收尾空格
  11.     str = strings.TrimSpace(str)
  12.     result := 0
  13.     sign := 1
  15.     for i, v := range str {
  16.         if v >= '0' && v <= '9' {
  17.             result = result*10 + int(v-'0')
  18.         } else if v == '-' && i == 0 {
  19.             sign = -1
  20.         } else if v == '+' && i == 0 {
  21.             sign = 1
  22.         } else {
  23.             break
  24.         }
  25.        // 数值最大检测
  26.         if result > math.MaxInt32 {
  27.             if sign == -1 {
  28.                 return math.MinInt32
  29.             }
  30.             return math.MaxInt32
  31.         }
  32.     }
  34.     return sign * result
  35. }
  37. func main() {
  38.     fmt.Println(myAtoi("42"))
  39.     fmt.Println(myAtoi(   " -42"))
  40.     fmt.Println(myAtoi("4193 with words"))
  41.     fmt.Println(myAtoi("words and 987"))
  42. }