If I get a segfault in Cygwin, what will that effect?

I am learning C++ using emacs on Cygwin, and I heard that in older Unix ope开发者_StackOverflowrating systems, a segfault can completely destroy critical memory. I know one idea with Cygwin was to make Windows more like Unix, so if I get a segfault on Cygwin, will that damage anything on Windows or Cygwin?

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No, it won't damage anything. It will just cause the application that triggered the segfault to crash. And probably (depending upon your Windows version and settings) you'll get an annoying popup message informing you of the crash, and asking if you want to report it.

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In modern operating systems (which include Linux, Win2K+ and MacOSX), every process can only access an area of "virtual memory" which is managed by the OS and cleaned up entirely after the process's lifetime finishes. A memory access error on part of the process that causes the process to be terminated simply means that the process has tried to access part of its virtual address space which it has not informed the OS about and which the OS did not want to process to access, but this does not affect anything outside that one process. There is no direct access to "real" memory for userspace processes, and thus you cannot really do a huge amount of harm.

(OK, I'm glossing over things, if you accidentally triggered an API call to "kill" and you had admin privileges, I suppose you could cause some harm. But you know what I mean.)