newbie code query => Arduino & DS18B20
In C, just about any data type can be represented as an array of bytes.  Without getting into a complete course on data types and pointers in C (which I'm not really qualified to do, anyway), the following should work on the transmitting end:

float tempC = sensors.getTempCByIndex(0);
client.sendto(11, (uint8_t *)&amp;tempC, sizeof(tempC));


On the receiving end, you'd do something like this:

float tempC;
server.recv((uint8_t *)&amp;tempC, sizeof(tempC));