Every calculation, & say what mean

ClassID= wait_event_info & 0xFF000000 = 0x3000004U & 0xFF000000 = 0x3000000U

What does the & mean?

How can I calculate the above value, please give pointers

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Other Answer 1:

https://www.its404.com/article/weixin_34878397/113440744

Look at this

Other Answer 2:

& is a bitwise AND operation