c++ - 错误: switch quantity not an integer switch ((MPI_Datatype) datatype){

Question

我正在尝试编写 MPI_Reduce(....) 代码。我发现以下代码，但它在 switch 语句中给了我错误:

#include <iostream>
#include <fstream>
#include <cmath>
#include <mpi.h>
#include <ctime>
#include <vector>

#define MYBUFFERLENGTH 1024
char myinbuffer[MYBUFFERLENGTH];
char myoutbuffer[MYBUFFERLENGTH];

extern "C" {
    int mikes_MPI_SIZE (MPI_Datatype datatype) {
    /* sizeof doesn't work for MPI_Datatype, thus this function */
    /* I probably should do this with a table, but then error
    checking is harder */
   /* see man MPI_COMM_WORLD */
       switch ((MPI_Datatype) datatype){
       /* case MPI_CHAR:
       case MPI_BYTE:
       case MPI_UNSIGNED_CHAR:
          return sizeof(char);
       case MPI_SHORT:
       case MPI_UNSIGNED_SHORT:
          return sizeof(short);
       case MPI_INT:
       case MPI_UNSIGNED:
          return sizeof(int);
       case MPI_LONG:
       case MPI_UNSIGNED_LONG:
          return sizeof(long);
       case MPI_FLOAT:
         return sizeof(float);
       case MPI_DOUBLE:
         return sizeof(double);
       case MPI_FLOAT_INT:
         return sizeof(float)+sizeof(int);
       case MPI_LONG_INT:
         return sizeof(long)+sizeof(int);
       case MPI_DOUBLE_INT:
         return sizeof(double)+sizeof(int);
       case MPI_SHORT_INT:
         return sizeof(short)+sizeof(int);
       case MPI_2INT:
         return 2*sizeof(int);
       default:
         die("need to insert size for new datatype in  mikes_MPI_SIZE()");*/
   }
  return -1;
}

 int MMPI_Reduce(void * sendbuf, void * recvbuf, int count, MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm)
{
    int bit,processor1,i;

    int *iaccum1;
    int *iaccum2;
    double *daccum1;
    double *daccum2;
    int * locaccum1;
    int * locaccum2;
    iaccum1=(int *) myinbuffer;
    iaccum2=(int *)(myinbuffer+mikes_MPI_SIZE(datatype));
    daccum1=(double *) myinbuffer;
    daccum2=(double *)(myinbuffer+mikes_MPI_SIZE(datatype));
    locaccum1=(int*)(myinbuffer+mikes_MPI_SIZE(datatype)-sizeof(int));
    locaccum2=(int*)(myinbuffer+2*mikes_MPI_SIZE(datatype)- sizeof(int));
    *locaccum1=*locaccum2=processor1;
    return MPI_SUCCESS;
  }

当我使用 mpic++ 编译它时，出现以下错误:

$ mpic++ reduce.cpp reduce.cpp: In function ‘int mikes_MPI_SIZE(MPI_Datatype)’: reduce.cpp:18:36: error: switch quantity not an integer switch ((MPI_Datatype) datatype){ ^ reduce.cpp: At global scope: reduce.cpp:70:3: error: expected ‘}’ at end of input }

我该如何解决这个问题？

Answer 1

感谢您的指导，但相信我，我没有阅读您的解决方案。我尝试了 if-else 并且成功了。

#include <iostream>
#include <fstream>
#include <cmath>
#include <mpi.h>
#include <ctime>
#include <vector>

#define MYBUFFERLENGTH 1024
char myinbuffer[MYBUFFERLENGTH];
char myoutbuffer[MYBUFFERLENGTH];

extern "C" {
  int mikes_MPI_SIZE (MPI_Datatype datatype) {
  if(datatype ==MPI_CHAR){
    return sizeof(char);
  }
  else if(datatype == MPI_DOUBLE){
    return sizeof(double);
  }
  return -1;
  }
}


int MMPI_Reduce(void * sendbuf, void * recvbuf, int count, 
     MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm) {

int bit,processor1,i;

int *iaccum1;
int *iaccum2;
double *daccum1;
double *daccum2;
int * locaccum1;
int * locaccum2;
iaccum1=(int *) myinbuffer;
iaccum2=(int *)(myinbuffer+mikes_MPI_SIZE(datatype));
daccum1=(double *) myinbuffer;
daccum2=(double *)(myinbuffer+mikes_MPI_SIZE(datatype));
locaccum1=(int*)(myinbuffer+mikes_MPI_SIZE(datatype)-sizeof(int));
locaccum2=(int*)(myinbuffer+2*mikes_MPI_SIZE(datatype)-sizeof(int));
*locaccum1=*locaccum2=processor1;
return MPI_SUCCESS;
}

int main(){
}