WiFi : WiFiUDP.parsePacket()
It starts processing the next available incoming packet, checks for the presence of a UDP packet, and reports the size. parsePacket() must be called before reading the buffer with UDP.read().
Corrections, suggestions, and new documentation should be posted to the Forum.
The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.