golang调用c结构体时的字节对齐问题

c结构体按1字节对齐时, 结构体Fc_tgs_struct与Fc_tgs_struct_2的大小不一致,谁能解答一下 --------------------------------struct.h-------------------------------- #ifndef HEAD_STRUCT_C #define HEAD_STRUCT_C #include <stdio.h> #define BYTE_PACK_ON #ifdef BYTE_PACK_ON #pragma pack(1) #endif struct Fc_tgs_struct { char cFlag; unsigned int uTime; char sName[32]; char sPwd[64]; long long llVal; }; struct Fc_tgs_struct_2 { unsigned int uTime; char sName[32]; char sPwd[64]; long long llVal; char cFlag; }; #ifdef BYTE_PACK_ON #pragma pack() #endif #endif /// HEAD_STRUCT_C --------------------------------cCallDemo.go-------------------------------- /** * Created by huQg on 2018/5/31,031. */ package cCallDemo /* #include "struct.h" */ import "C" import ( "fmt" "unsafe" ) func calccCallStruct() { ctg := C.struct_Fc_tgs_struct{} isz := unsafe.Sizeof(ctg) fmt.Printf("struct Fc_tgs_struct's size = %d\n", isz) ctg2 := C.struct_Fc_tgs_struct_2{} isz = unsafe.Sizeof(ctg2) fmt.Printf("struct Fc_tgs_struct_2's size = %d\n", isz) } --------------------------------cCallDemo_test.go-------------------------------- /* * Created by huQg on 2018/5/31,031. */ package cCallDemo import ( "testing" ) func TestXYZ(t *testing.T) { /// struct calccCallStruct() }