strconv 包代码阅读

strconv 包含了一系列的转换函数：

字符串转整型

转整型定义了新的错误类型：

type NumError struct {
    Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat, ParseComplex)
    Num  string // the input
    Err  error  // the reason the conversion failed (e.g. ErrRange, ErrSyntax, etc.)
}

func (e *NumError) Error() string {
    return "strconv." + e.Func + ": " + "parsing " + Quote(e.Num) + ": " + e.Err.Error()
}

func (e *NumError) Unwrap() error { return e.Err }

var ErrSyntax = errors.New("invalid syntax")
func syntaxError(fn, str string) *NumError {
    return &NumError{fn, str, ErrSyntax}
}

var ErrRange = errors.New("value out of range")
func rangeError(fn, str string) *NumError {
    return &NumError{fn, str, ErrRange}
}

func baseError(fn, str string, base int) *NumError {
    return &NumError{fn, str, errors.New("invalid base " + Itoa(base))}
}

func bitSizeError(fn, str string, bitSize int) *NumError {
    return &NumError{fn, str, errors.New("invalid bit size " + Itoa(bitSize))}
}

其他：

const intSize = 32 << (^uint(0) >> 63)
const IntSize = intSize
const maxUint64 = 1<<64 - 1

• ParseUint

  func ParseUint(s string, base int, bitSize int) (uint64, error) {
      const fnParseUint = "ParseUint"
  
      if s == "" {
          return 0, syntaxError(fnParseUint, s)
      } 
      
      base0 := base == 0
  
      // 查看是什么进制转换，输入"0b", "0o", "0x"
      s0 := s
      switch {
      case 2 <= base && base <= 36:
        // valid base; nothing to do
      case base == 0:
      // Look for octal, hex prefix.
          base = 10
          if s[0] == '0' {
              switch {
              case len(s) >= 3 && lower(s[1]) == 'b':
                  base = 2
                  s = s[2:]
              case len(s) >= 3 && lower(s[1]) == 'o':
                  base = 8
                  s = s[2:]
              case len(s) >= 3 && lower(s[1]) == 'x':
                  base = 16
                  s = s[2:]
              default:
                  base = 8
                  s = s[1:]
              }
          }
      default:
          return 0, baseError(fnParseUint, s0, base)
      }
  
      if bitSize == 0 {
          bitSize = IntSize
      } else if bitSize < 0 || bitSize > 64 {
          return 0, bitSizeError(fnParseUint, s0, bitSize)
      }
  
  }
  

字符串转浮点

字符串转bool

• 字符串和bool

  func ParseBool(str string) (bool, error) {
      switch str {
      case "1", "t", "T", "true", "TRUE", "True":
          return true, nil
      case "0", "f", "F", "false", "FALSE", "False":
          return false, nil
      }
      return false, syntaxError("ParseBool", str)
  }
  

• bool 转 字符串

  func FormatBool(b bool) string {
      if b {
          return "true"
      }
      return "false"
  }
  

字符串转复数

TODO