I am trying to call C methods from  python script, C method calls inturn the C++ method. I am allocating array inside the getResults() method using malloc(). Now the issue is how to pass the arguments to float* oresults in python script whose memory allocation takes place inside the C layer. This is io.c

https://bit.ly/30VrFbR

int getResults(char* iFilename, char* iStagename, int iStateidCnt, 
    int* Stateids, int iEntityIdCount, int* iEntityids, char* iEntityType,
    char* iVariablegroup, char* ivariable, int *oRescount,
    float* oResults)
    int Status, i;
        EString etype(iEntityType), stagename(iStagename);
    EString vargroup(iVariablegroup);
    std::vector<ERF_INT> entity_ids;
    std::vector<ERF_INT> stateids;
    std::vector<ERF_FLOAT> results;
    _CopyIntArrayIntoVector(iStateidCnt, Stateids, stateids);
    _CopyIntArrayIntoVector(iEntityIdCount, iEntityids, entity_ids);
    CreateIoInstance(iFilename, iStagename);
    ioData pIodata = CreateIoDataInstance();
    if (iEntityIdCount <= 0)
        pIodata.setWholeSection(true);
        pIodata.setWholeSection(false);
        pIodata.setEntityList(entity_ids);
    pIodata.setStateList(stateids);
    pIodata.setType(etype);
    pIodata.setVariableGroup(iVariablegroup);
    pIodata.setVariable(ivariable);
        //This is C++ method
    Status = pIo->get_results(pIodata, results);
    *oRescount = results.size();
        //allocation for oresults whose size > 2
    oResults = (float*)malloc(results.size() * sizeof(float));
    _CopyVectorIntoDoubleArray(results, oResults);
    return Status;

test.py

from ctypes import *
import os, sys
dll = CDLL('D:\\erf_utils_python\\erf_utils_io.dll')
dll.getresults.argtypes = (c_char_p,c_char_p,c_int,POINTER(c_int),c_int,POINTER(c_int),c_char_p,
                                  c_char_p,c_char_p,POINTER(c_int),POINTER(c_float))
dll.getresults.restype = c_int
def make_array(ctype,arr):
    return len(arr),(ctype * len(arr))(*arr)
def getresults(filename,stagename,sids,eids,entitytype,groups,variables):
    if(len(sids)>0):
       stateidcount,stateids = make_array(c_int,sids)
    if(len(eids)>0):
       entityidcount,entityid = make_array(c_int,eids)
    oresultlen = c_int()
    float_values = POINTER(c_float)
    err = dll.getresults(filename,stagename,stateidcount,stateids,entityidcount,entityid,
                                entitytype,groups,variables,byref(oresultlen), byref(float_values))
    return err,oresultlen.value, float_values
filename = b'D:\\inputfile.h5'
stagename = b"post"
stateids = [2]
stateidcount = 1
entityidcount = 1
entityid = [1]
entitytype = b"test"
variablecount = 1
variablegroup = b"testdata"
variable = b"next"
err,oreslen,ores = getresults(filename,stagename,stateids,entityid,entitytype,variablegroup,variable)

TypeError: byref() argument must be a ctypes instance, not '_ctypes.PyCPointerType' this is the error I get when I run the script. I am little confused on how to send argument for float *oresults in script.