void ontriggerenter(collider other) not working code example

Example 1: void OntriggerEnter (Collider other)

void OntriggerEnter (Collider other)

Example 2: void ontriggerenter not working

2D for 2D (OnTriggerEnter2D) and 3D for 3D (OnTriggerEnter)
at least one object needs to have rigibody, and collider set to isTrigger

yea and this is for unity game engine only