dst := float32(src)

var num int = 520
f32 := float32(num)
i64 := int64(num)

dst,ok := src.(int) // 安全類型斷言,通過ok判斷是否轉換成功
dst := src.(int)　  // 非安全類型斷言，無法確定是否轉換成功

var val interface{} = 123
num,ok := val.(int)
if ok {
    fmt.Printf("%T->%d\n", num, num)
} else {
    fmt.Println("類型不匹配")
}

//類型轉換  string to bytes 
func str2bytes(s string) []byte { 
    x := (*[2]uintptr)(unsafe.Pointer(s)) 
    h := [3]uintptr{x[0], x[1], x[1]} 
    return *(*[]byte)(unsafe.Pointer(h)) 
}
//類型轉換  bytes to string 
func bytes2str(b []byte) string { 
    return *(*string)(unsafe.Pointer(b)) 
}

//interface轉為string 
func interface2string(inter interface{}) string { 
    tempStr := "" 
    switch inter.(type) { 
        case string: tempStr = inter.(string) break 
        case float64: tempStr = strconv.FormatFloat(inter.(float64), 'f', -1, 64) break 
        case int64: tempStr = strconv.FormatInt(inter.(int64), 10) break 
        case int: tempStr = strconv.Itoa(inter.(int)) break 
 } 
    return tempStr 
}

//整形轉字符串
strconv.Itoa(100)
//該方法的源碼是：
//可以看出是FormatInt方法的簡單實現。
func Itoa(i int) string {
        return FormatInt(int64(i), 10)
}
//字符串轉整形
i, _ := strconv.Atoi("100")
//64位整形轉字符串,FormatInt第二個參數表示進制，10表示十進制
var i int64
i = 0x100
strconv.FormatInt(i, 10)
//字節轉32位整形
b := []byte{0x00, 0x00, 0x03, 0xe8}
bytesBuffer := bytes.NewBuffer(b)
//其中binary.BigEndian表示字節序，相應的還有little endian。通俗的說法叫大端、小端。
var x int32
binary.Read(bytesBuffer, binary.BigEndian, x)
fmt.Println(x)
//32位整形轉字節
var x int32
x = 106
bytesBuffer := bytes.NewBuffer([]byte{})
binary.Write(bytesBuffer, binary.BigEndian, x)
fmt.Println(bytesBuffer.Bytes())
//字節轉字符串
fmt.Println(string([]byte{97, 98, 99, 100}))
//字符串轉字節
fmt.Println([]byte("abcd")) 

//string-->unicode
func Str2uft16ptr(str string)(p uintptr){//將字符串轉為utf16指針
 e:=utf16.Encode([]rune(str))//轉成unicode
 e=append(e, uint16(0))//添加末尾的0
 p=uintptr(unsafe.Pointer(e[0]))//轉成指針
 //p=uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(str)))
 return
}
//unicode-->string
func addbuf(buf []uint16,newcap int)(newbuf []uint16){
 newbuf=make([]uint16,newcap)
 copy(newbuf,buf)
 return
}
func Utf16prt2str(p uintptr)(str string){//將utf16指針轉為字符串
 len:=0
 buf:=make([]uint16,64)
 for a:=(*(*uint16)(unsafe.Pointer(p)));a!=0;len++{
  if len>=cap(buf){
   buf=addbuf(buf,len*2)
  }
  buf[len]=a
  p+=2//uint16占2字節
  a=(*(*uint16)(unsafe.Pointer(p)))
 }
 str=string(utf16.Decode(buf[:len]))
 return
}

#cgo
char -->  C.char -->  byte
signed char -->  C.schar -->  int8
unsigned char -->  C.uchar -->  uint8
short int -->  C.short -->  int16
short unsigned int -->  C.ushort -->  uint16
int -->  C.int -->  int
unsigned int -->  C.uint -->  uint32
long int -->  C.long -->  int32 or int64
long unsigned int -->  C.ulong -->  uint32 or uint64
long long int -->  C.longlong -->  int64
long long unsigned int -->  C.ulonglong -->  uint64
float -->  C.float -->  float32
double -->  C.double -->  float64
wchar_t -->  C.wchar_t  -->  
void * -> unsafe.Pointer
#window
uint64 //對應SIZE_T
uint32 //對應DWORD

//整型數
//Go->C：
var i int
ci := C.int(i)
//C->Go：
var i C.int
goi := int(i)
//數組和字符串
//Go->C：
var str string
cstr := C.CString(str)
//C->Go：
/*
#include stdlib.h>
#include stdio.h>
char foo[] = "hellofoo";
char *bar = "hellobar";
*/
import "C"
import "fmt"
func main() {
    fmt.Printf("%s\n", C.GoString(C.foo[0]))
    fmt.Printf("%s\n", C.GoString(C.bar))
}
//數組類型轉換
/*
#include stdio.h>
int cIArray[] = {1, 2, 3, 4, 5, 6, 7}; //int
float cFArray[] = {1.011, 2.022, 3.022, 4.023, 5.02, 6.03, 7.045};//float
*/
import "C"
import "fmt"
func main() {
    goIArray := C.cIArray[:]
    fmt.Println(goIArray)
    goFArray := C.cFArray[:]
    fmt.Println(goFArray)
}
//[]byte 轉換為 *char
c_char := (*C.char)(unsafe.Pointer(bt[0]))