###### tags: `Golang Package`

# Cast
https://segmentfault.com/a/1190000021684109
類型轉換庫，將字串轉數字、數字轉字串、轉成布林值等。

## ToString

fmt.Println(cast.ToString("leedarjun"))        // leedarjun
fmt.Println(cast.ToString(8))                  // 8
fmt.Println(cast.ToString(8.31))               // 8.31
fmt.Println(cast.ToString([]byte("one time"))) // one time
fmt.Println(cast.ToString(nil))                // ""
fmt.Println(cast.ToString(false)) 	         // false

## ToInt

fmt.Println(cast.ToInt(8))     // 8
fmt.Println(cast.ToInt(8.31))  // 8
fmt.Println(cast.ToInt("8"))   // 8
fmt.Println(cast.ToInt(true))  // 1
fmt.Println(cast.ToInt(false)) // 0

## ToBool

fmt.Println(cast.ToBool("1")) // true
fmt.Println(cast.ToBool(1))   // true
fmt.Println(cast.ToBool(nil)) // false
fmt.Println(cast.ToBool("2")) // false

## ToSliceBool

	fmt.Println(cast.ToBoolSlice([]string{"1", "0"})) // [ture false]

## ToDuration

fmt.Println(cast.ToDuration(1398173719283712328))
// 388381h35m19.283712328s

// ---------------------------------------------------------------
func ToDurationE(i interface{}) (d time.Duration, err error) {
	i = indirect(i)

	switch s := i.(type) {
	case time.Duration:
		return s, nil
	case int, int64, int32, int16, int8, uint, uint64, uint32, uint16, uint8:
		d = time.Duration(ToInt64(s))
		return
	case float32, float64:
		d = time.Duration(ToFloat64(s))
		return
	case string:
		if strings.ContainsAny(s, "nsuµmh") {
			d, err = time.ParseDuration(s)
		} else {
			d, err = time.ParseDuration(s + "ns")
		}
		return
	default:
		err = fmt.Errorf("unable to cast %#v of type %T to Duration", i, i)
		return
	}
}

## ToFloat32

fmt.Println(cast.ToFloat32("239.1"))   // 239.1
fmt.Println(cast.ToFloat32(int64(192)))// 192
fmt.Println(cast.ToFloat32(false))     // 0

## ToStringMap

	fmt.Println(cast.ToStringMap(map[string]interface{}{
		"one":   "1",
		"two":   2,
		"three": float32(3.4),
		"four":  uint8(5),
		"five":  false,
	}))
/* 
 (map[string]interface {}) (len=5) {
 (string) (len=5) "three": (float32) 3.4,
 (string) (len=4) "four": (uint8) 5,
 (string) (len=4) "five": (bool) false,
 (string) (len=3) "one": (string) (len=1) "1",
 (string) (len=3) "two": (int) 2
}
*/

## ToStringMapString

spew.Dump(cast.ToStringMapString(map[string]interface{}{
		"one":   "1",
		"two":   2,
		"three": float32(3.4),
		"four":  uint8(5),
		"five":  false,
	}))
/*
(map[string]string) (len=5) {
 (string) (len=3) "two": (string) (len=1) "2",
 (string) (len=5) "three": (string) (len=3) "3.4",
 (string) (len=4) "four": (string) (len=1) "5",
 (string) (len=4) "five": (string) (len=5) "false",
 (string) (len=3) "one": (string) (len=1) "1"
}
*/

## ToStringMapStringSlice

	spew.Dump(cast.ToStringMapStringSlice(map[string][]interface{}{
		"animal": {"dog", "cat"},
		"bool":   {true, false},
		"card":   {1, 2, 3, 4, 5},
	}))
/*
(map[string][]string) (len=3) {
 (string) (len=4) "card": ([]string) (len=5 cap=8) {
  (string) (len=1) "1",
  (string) (len=1) "2",
  (string) (len=1) "3",
  (string) (len=1) "4",
  (string) (len=1) "5"
 },
 (string) (len=6) "animal": ([]string) (len=2 cap=2) {
  (string) (len=3) "dog",
  (string) (len=3) "cat"
 },
 (string) (len=4) "bool": ([]string) (len=2 cap=2) {
  (string) (len=4) "true",
  (string) (len=5) "false"
 }
}
*/


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