在Java中从C读取长字节

Question

I have to send a long from my c program to be read in java code using a byte buffer . I am doing something wrong as i cant send 1234 and read it back in java as it gets corrupted to 564049465049088.

In my C code I do

int64_t resultl = 1234;

Then to copy

uint8_t * outBuffer <== pointer to the buffer;
memcpy(outBuffer,&resultl,8);

In java I read back the bytes as

ByteBuffer buf = ByteBuffer.wrap(bytes);

offset=0;
long l = buf.getLong(offset);

This is giving me wrong value 564049465049088 as i had sent 1234 from C; Can someone please suggest what I am doing wrong & how can i correct the same.

Answer 1

You have to change the endianness of the ByteBuffer:

ByteBuffer buf = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);

since you are probably on a little-endian computer system (x86 and most ARM systems).