Using wiringPi & digitalRead yields varying states with a dangling dupont wire

[JohnQPublic]

I have a small C program where a GPIO pin on Orange Pi is polled using digitalRead. It works fine and detects HIGH and LOW as expected. When I put a dupont wire with nothing connected at the other end (ie. just extend the GPIO pin) digitalRead starts registering intermittent HIGHs and LOWs wildly. What the heck am I seeing? I have a Raspberry 3 nearby and it does not show this phenomenom.

Using digitalWrite on the pin works as expected.

[martinayotte]

Did you use either internal PullUp or external PullUp to 3.3V ?

If not, the wire is acting as an antenna with random states.