golang Read(p []byte) doesnot read full byte? : Recently I use golang Read(p []byte),intending to read full len(p) bytes. However I find that Read does not guarantee read len(p) bytes.That's,I need read 4 bytes but actually it gives me only 1.At last I use io.ReadFull instead.Now I am confused, what's the meaning of the function? What's the proper scene using Read?It may just read less bytes than you need.  