Exception in GCC-compiled segmentation fault

Debug todayProgram, Add some new variables to the program, and other variables have not been moved.

When a program is run, the result is that an int * type epoch variable is changed to null, which is a newly added variable. After checking for two hours, we found that the problem was that epoch was not null during initialization, but it was very confusing to program null during running. No debugging result was returned.

Later, I accidentally make clean, deleted all *. O, compiled from scratch, and found that the problem was solved...

This may be because makefile is not well written and the dependency is incomplete. As a result, the. o file of previous versions is used in make, and the link becomes problematic.