Field values for nested structs not getting set in protobuf - c++

Question

I am using google protobuffer for data deserialization, but my issue is that the field values for the nested structures are not getting set. I checked the bin file in a hex editor and the values look fine. However, since the first field in my nested struct is a float and if I try to get the corresponding number of bytes and decode it into a float, the value seems fine.
Can someone advice what else I can do to check this or what perhaps is happening? I have tried using ParseFromIstream as well.
the proto file is :
syntax = "proto3";
package generatedata;
message DataSample {
DataSample_Safe DataSafe = 1;
uint32 PassReSts = 2;
uint32 Dir = 3;
}
message DataSample_Safe {
float ALast = 1;
uint32 ALastQf = 2;
}
message DataSampleMultiple
{
repeated DataSample finaldata = 1;
}
The C++ code is
fstream in("test.bin", ios::in | ios::binary);
generatedata::DataSample test_data;
while(in.read((char *) &test_data,sizeof(test_data)))
{
const generatedata::DataSample_Safe& veh = test_data.datasafe();
cout << "safe" << veh.alast() << endl;
cout << "First " << test_data.passrests() << endl;
cout << "Second " << test_data.dir() << endl;
}
Using ParseFromIstream, the code is
generatedata::DataSampleMultiple test_data;
test_data.ParseFromIstream(&in);
for(int i = 0 ; i < test_data.finaldata_size(); i ++)
{
const generatedata::DataSample& veh = test_data.finaldata(i);
const generatedata::DataSample_Safe& check = veh.datasafe();
cout << "safe" << check.alast() << endl;
cout << "First " << veh.passrests() << endl;
cout << "Second " << veh.dir() << endl;
}
in the above case using ParseFromIstream, the final data size is 0
The first cout gives segmentation fault as the value of safe has not been set. However, the second and third couts are output correctly when using istream::read