I would like to control the output of the below random function. I want that it return a number between the min and the max parameters. but it didn't. can you tell what should I change to do that. in the web, I found that 10000 should be the maximun that can be generated
I use a f340 with the tcp-ip conf wiz.
int random(int min, int max){ int res = min + (int)(my_rand()/10000*(max-1)); return res; }
You have also forgotten (a second time) to read the information how to post source code, despite Andy specifically notifying you about it - and posting a link.
Now, it is time for you to pick up the documentation for rand(). It normally returns integer values between 0 and RAND_MAX, so RAND_MAX should be a good constant to make use of.
It is quite unlikely that your RAND_MAX is 10000. A more common value is 32767 or 65535 or any other 2^n-1 value.
sorry for the wrong code and thanks for your answer. I took the code on the web. res = ( my_rand()%(max-min) ) + min; did exactly what I want. thanks
I took the code on the web.
Don't blindly take code from the web without understanding what it does.
res = ( my_rand()%(max-min) ) + min;
did exactly what I want.
Are you really sure it does exactly what you want ? The above line will not produce pseudorandom numbers that are evenly distributed (i.e. each of the numbers has the same probability of occurring). It's like rolling loaded dice.
I use this function to simulate a graphic chart, I just want that values change each time. I understand what you said about probability of occuring. can you tell me the way to make it right?
I understand what you said about probability of occuring. can you tell me the way to make it right?
Somewhat better in terms of distribution would be:
long tmp; tmp = my_rand(); tmp = tmp * (max - min); tmp = (tmp + (MAX_RAND / 2)) / MAX_RAND; tmp = tmp + min;
Of course, the price to pay is additional computational effort (multiplication and division take a while on a '51, especially with long integers).
Of course, the price to pay is additional computational effort (multiplication and division take a while on a '51, especially with long integers). he clearly does not care about that, he uses an int for TRUE/FALSE. He crossposted at the SILabs forum www.cygnal.org/.../002446.html
Erik