run incorrecly using -O?

[Onix]

I wrote a program and when compile it with g++ without optimized
option -O, the final program runs correctly, but if I compile it using
-O then the final program produced error.

Is there anything I need to aware when using -O?

 

[utab]

I wrote a program and when compile it with g++ without optimized
option -O, the final program runs correctly, but if I compile it using
-O then the final program produced error.

Is there anything I need to aware when using -O?

It is best if you paste some code to comment on?

Rgds,

 

[red floyd]

Your program most likely has undefined behaviour which changes if it
is compiled (optimized) a bit more than not at all. You need to aware
how to debug your program, and spend some time doing that.

That's not necessarily the case. I dealt with some (C -- not C++) code
where gcc did some overly aggressive optimizations that led to segfaults
and bus errors (granted, the code was using ugly constructs, but they
were well-defined).