Is C assigned a stack for every {}?

As you asked, you can declare a variable on the top line of the brace, and if you leave the area, you can no longer use the identifier It may look similar to a stack to a programmer's

C's brace ({{}) is not a stack frame, but naming scope), so entering the brace does not push/pop into the stack.

The code you asked is theoretically an array d holds memory throughout the foo function.