NewPing Library: HC-SR04, SRF05, SRF06, DYP-ME007, Parallax PING))) - v1.7

Using Arduino Sensors
12

Agree with AWOL's proposal , especially as the original code mixes type (false=bool and ints)

you can even make it a macro:

#define convert_cm(echotime) ((echoTime) / US_ROUNDTRIP_CM)