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• You can see the answer to this question https://ask.csdn.net/questions/7559176 < / font > < / a > < / li > < li > I also find you a very good blog, you can see if it helps, link: switch case
• In the meantime, you can also check the manual: < a href = "https://zh.cppreference.com/w/c/language/switch" target = "_blank" > < font size = "3" > c language - switch < / font > < / a >

x=20; =10 is valid, enter case1(where 0 represents false and 1 represents true)
and then judge x> =30 does not hold, enter case0, y=62

Where's the loop? It's a sequential structure, there's no loop.
You don't even have branches and loops.
You can think of switch as a bunch of ifs, Whatever expression is in the switch will enter the corresponding case, x=20 x> =10 is 1, how can I execute case 0, I have to execute case 1