golang怎么返回结构体？

Question

golang怎么返回结构体

Answer 1

用golang解析二进制协议时，其实没必要管结构体的字段的对齐规则，何况语言规范也没有规定如何对齐，也就是没有规则。用encoding/binary.Read函数直接读入struct里就行，struct就像c那样写type Data struct {Size, MsgType uint16Sequence uint32// ...}golang编译器加不加padding，Read都能正常工作，runtime知道Data的布局的，不像C直接做cast所以要知道怎样对齐。用unsafe.Alignof可以知道每个field的对齐长度，但没必要用到。package main/*#include <stdint.h>#pragma pack(push, 1)typedef struct {uint16_t size;uint16_t msgtype;uint32_t sequnce;uint8_t data1;uint32_t data2;uint16_t data3;} mydata;#pragma pack(pop)mydata foo = {1, 2, 3, 4, 5, 6,};int size() {return sizeof(mydata);}*/import "C"import ("bytes""encoding/binary""fmt""log""unsafe")func main() {bs := C.GoBytes(unsafe.Pointer(&C.foo), C.size())fmt.Printf("len %d data %v\n", len(bs), bs)var data struct {Size, Msytype uint16Sequence uint32Data1 uint8Data2 uint32Data3 uint16}err := binary.Read(bytes.NewReader(bs), binary.LittleEndian, &data)if err != nil {log.Fatal(err)}fmt.Printf("%v\n", data) // {1 2 3 4 5 6}buf := new(bytes.Buffer)binary.Write(buf, binary.BigEndian, data)fmt.Printf("%d %v\n", buf.Len(), buf.Bytes()) // 15 [0 1 0 2 0 0 0 3 4 0 0 0 5 0 6]}