When does initialization of static member variables occur?

[Joseph Turian]

When does initialization of static member variables occur?

In the following code fragment, is m_start_time automatically
initialized right before main()?
[This is the desired effect.]

Or is m_start_time uninitialized until the first time I use a static
method in stats?

Thanks

Joseph

==

stats.H:
class stats {
...
static time_t m_start_time;
};

==

stats.C:
time_t get_start_time() {
time_t t;
time(&t);
return t;
}

time_t stats::m_start_time = get_start_time();

==

 

[Victor Bazarov]

When does initialization of static member variables occur?

At some point before 'main' is called, if they are defined.

In the following code fragment, is m_start_time automatically
initialized right before main()?
Yes.

[This is the desired effect.]

Or is m_start_time uninitialized until the first time I use a static
method in stats?
No.


Thanks

Joseph

==

stats.H:
class stats {
...
static time_t m_start_time;
};

==

stats.C:
time_t get_start_time() {
time_t t;
time(&t);
return t;

Why couldn't you just write

return time(0);

instead of the three lines?

}

time_t stats::m_start_time = get_start_time();

==

V

 

[Greg]

At some point before 'main' is called, if they are defined.


Yes.

Not necessarily. It is certain that m_start_time will be
zero-iniitalized before main() executes. But since m_start_time is not
initialized with a constant expression, its initialization is dynamic,
not static. §3.6.2/1. Therefore, it is implementation-defined whether
m_start_time will be initialized before main() is called. In other
words, your compiler documentation will have the answer to this
question.

[This is the desired effect.]

Or is m_start_time uninitialized until the first time I use a static
method in stats?

No.

Possibly. It is certain that m_start_time will be completely
initialized before the first use of any object or function in its
translation unit (i.e. source file) §3.6.2/3. Of course such use could
occur well after the program has started.

Greg