Hello Aspirant,
If you are in Bangalore, localites (especially auto rickshaw/shopkeepers) expect you to speak in their native language that is Kannada. I think it's quite obvious! Else everywhere people prefer speaking English over Kannada or Hindi and that is because it's a metropolitan with immigrants from all over the world.
Though you will have a mixture of students, one of my friends tells me that they are very warm people and students from different states come together most students speak in English. You might also find some students from your native state. But according to my experience, most people there know English and even most autorickshaw drivers and shop keepers too speak in English. I didn't face many problems with the language there.
Good luck!
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