My problem is not that i do get the same sequence.
My problem is that the first time i get a different sequence than the following
time even though i always use the same seed.
This only happens in a gtkmm application:
- call srand() with fixed value in the GtkWindow constructor
- call rand() when the 'step' button is pressed
- several presses on the 'step' button yield first sequence:
1935233081
645150759
1041788230
711017215
- now i press the 'reset' button which calls srand() with the same
seed as used in the constructor
- i repeatedly press 'the step' button
This gives the second sequence which differs from the first sequence;
1889402444
1202690506
785052894
61279049
Now, whenever i press te reset button, i get the same sequence of
numbers from the 'step' button.
Only when i restart the application i get the "bad" sequence again.
A simple console application always delivers the same sequence (the
same as the second one in my gtkmm app).
@oscar: did you make sure *not* to press the reset button before you
press the 'step' button the first time? So that
the first call to random() follows the srand() call triggered in the
constructor?
BTW: I have gtkmmmm 2.16.0 and gtk+ 2.16.6
Jody
On Tue, Jun 15, 2010 at 9:03 PM, Eric Wolf <[email protected]> wrote:
> Alexey Savartsov <[email protected]> writes:
>
>> The problem is that you always calling srand with same seed parameter. So
>> you always get same random sequence.
>>
>> Usually, srand called with the current time value like:
>>
>> srand(time(0));
>>
>> May be you need type casting of time() return value - follow compiler
>> warnings there.
>
> Another possibility —at least in linux— is reading some bytes
> from /dev/urandom and use these as seed.
>
> Maybe random/srandom should be used instead of rand, because
> man 3 advertise them as being more random than rand (tm).
> Whatever this means ...
>
> Eric
>
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