Zac Efron ''learned the hard way'' to pay attention to the people he's with.

The 'Extremely Wicked, Shockingly Evil and Vile' star has warned others to be careful who they associate with, as he seemingly hinted he had personal experience of this.

Speaking to Entertainment Tonight, he said: ''In a world where we swipe left and swipe right and you meet people, friends come and go, you really should pay attention to who you're with. I learned this [lesson] the hard way. And hopefully nobody else has to.''

Meanwhile, Zac previously revealed he relies on his younger brother Dylan for relationship advice.

He said: ''If I'm dating someone, one of the few people I need to weigh in on the situation is my brother. We live together, and we're different in a lot of ways, but he's really grounded. He lived a more normal life than I did growing up, so he's a great barometer for me. He'll be like, 'Are you sure you're happy? Is this what you really want?' Having my little brother around is a really great thing.''

And Zac - who has previously enjoyed relationships with his 'High School Musical' co-star Vanessa Hudgens from 2005 to 2010, and with model Sami Miro from 2014 to 2016 - is keen to settle down with the right girl now that he's in his 30s.

He said: ''I didn't think much about settling down until recently. Now that I'm in my 30s, I'm around some great relationships and I've seen expert couples at work. I'm realising that you have to find your own happiness before you can make somebody else happy.''