Using Qrand in qt

[samira]

hi,I want to know ,how to use generate value with qrand in qt?

[saman_artorious]

Call

qsrand(QTime::currentTime().msec())

once on application start. It will seed the random number generator.

Then generate the random numbers:

int nextNumber = rand() % 15 + 1;

int nextNumber = rand() % 15 + 1;

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[saman_artorious]

did it work fine?

[samira]

For converting range of

rand()(0-255)

into 0-1,is it correct if I use this code?

float nextNumber = (rand() % 10000) / 10000.0;

float nextNumber = (rand() % 10000) / 10000.0;

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Added after 4 minutes:

yes it seems work correct,but i want to sure about it

[saman_artorious]

Yes, this is correct.

[ChrisW67]

hi,I want to know ,how to use generate value with qrand in qt?

Assuming you want an integer value in the range 0 to N-1 for N < RAND_MAX then you just do this:

int value = qrand() % N;

int value = qrand() % N;

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However, it seems you wanted a random real value in the range 0 to 1.0, which qrand() does not produce directly:

qreal value = static_cast<qreal>(qrand()) / RAND_MAX ;

qreal value = static_cast<qreal>(qrand()) / RAND_MAX ;

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Be aware that RAND_MAX is typically fairly small and may give wide gaps between possible "random" floats.

Neither approach is suitable for cryptographic applications or where the uniformity of the random distribution is very important.