I am tring to read couple of bytes from byteData
as mentioned below in my C++ code. The actual value within byteData
is a binary blob byte array in BIG-ENDIAN byte order format. So I cannot simply just "cast" the byte array into a String..
byteData
byte array is composed of these three things -
First is `schemaId` which is of two bytes (short datatype in Java)
Second is `lastModifiedDate` which is of eight bytes (long datatype in Java)
Third is the length of actual `byteArray` within `byteData` which we need from `byteData`.
Fourth is the actual value of that `byteArray` in `byteData`.
Now I am trying to extract the above particular information from the byteData
in C++... Somehow I am able to extract schemaId
and the value which I am getting is also correct.. Now I am not sure how to extract other things from it...
uint16_t schemaId;
uint64_t lastModifiedDate;
uint16_t attributeLength; // or it should be uint32_t?
const char* actual_binary_value;
while (result.next()) {
for (size_t i = 0; i < result.column_count(); ++i) {
cql::cql_byte_t* byteData = NULL;
cql::cql_int_t size = 0;
result.get_data(i, &byteData, size);
// I cannot just "cast" the byte array into a String
// value = reinterpret_cast<char*>(byteData);
// this works fine
schemaId = ntohs(*reinterpret_cast<uint16_t*>(byteData));
// now how to retrieve lastModifiedDate, length of binary value and actual_binary_value from byteData?
// the below doesn't works..
lastModifiedDate = be64toh(*reinterpret_cast<uint64_t*>(data));
// And how to extract other things as well?
}
// this prints out `9223090561897746107` but it should print out `1289811105109`
cout<< lastModifiedDate <<endl;
// And print out other things..
}
If somebody needs to see my java code then this is my java code -
byte[] avroBinaryValue = text.getBytes();
long lastModifiedDate = 1289811105109L;
short schemaId = 32767;
int size = 2 + 8 + 4 + avroBinaryValue.length; // short is 2 bytes, long 8 and int 4
ByteBuffer bbuf = ByteBuffer.allocate(size);
bbuf.order(ByteOrder.BIG_ENDIAN);
bbuf.putShort(schemaId);
bbuf.putLong(lastModifiedDate);
bbuf.putInt(avroBinaryValue.length);
bbuf.put(avroBinaryValue);
// merge everything into one bytearray.
byte[] bytesToStore = bbuf.array();
Hex.encodeHexString(bytesToStore)
Can anybody help me what wrong I am doing in my C++ code and why I am not able to extract lastModifiedDate
properly from it and other fields as well? As I understand lastModifiedDate
is 64 bit integer, so is there any way to swap out 64 bit integer here? Or some other better way to do the conversion?
In short, I am trying to extract schemaId
, lastModifiedDate
, avroBinaryValue.length
and avroBinaryValue
from that byte array in C++..
I am able to extract schemaId
but I am stuck on other things now...