What happens when you try to access address 0x0 of virtual memory?

Question

C++ / C#

There are photos with addresses starting with 0x1000, 0x1008, 0x1010, 0x1018, etc.
What happens when you try to access address 0x0 of virtual memory?

Answer 1

In the context of the C++ language, there will be undefined behavior with unpredictable consequences. An optimizing compiler can reorder the execution sequence of a program to assume that a dereferenced pointer in a valid program cannot be 0.
In the context of program behavior, if address 0 is accessed, the behavior is OS/runtime dependent. Options -- SIGSEGV signal (POSIX) will be sent to the program, an exception will occur in the program (windows), access will be performed as to any other address (OS without memory protection).