* sheepbao <listome...@gmail.com> [180814 10:53]: > Thank you for your detailed answer. > I thought it would crash in this line (b.Z = "zz") of code. But it dose not > happen and the program print "zz". > I don't understand why this program crash in return, not in b.Z = "zz". > Because I agree with your opinion, The field Z of (*b) is beyond the > memory that was allocated > on the heap or reserved on the stack for a.
It does not crash when assigning to b.Z because b.Z references valid, writable memory. It overwrites what some other part of the code wrote there for a different purpose. It is not until the incorrect value is read and used for the original intended purpose that incorrect behavior can be noticed. If nothing ever reads from that location afterwards, than no incorrect behavior can be observed. It might crash when assigning to b.Z if that memory location is not writable or is not within the program's address space. This could happen, for instance, if the memory allocated for a were at the very end of the program's address space. This is extremely unlikely under most circumstances. Once you use unsafe to convert a pointer from one type to another, you become responsible for ensuring that your use is appropriate; the compiler no longer attempts to keep track of the memory to which the unsafe pointer points. ...Marvin -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
