Random Number

[Gunner54]

packet[siz] = (char)(rand()%255);

I want it to randomise a number between 1-255 that will ALWAYS have atleast a diffrence of 10. So it will NEVER generate a number thats 1-10 above or below the number it generated before.

e.g: generates 86 the next number has to be below 76 or above 96.

any help?

[sunburnt]

You just need to keep track of the old number, then do something like this:

char new_rand = (old_rand - 20) + rand() % 21
old_rand = new_rand;

What I do is subtract 20 from the old value, then add a random number from 0-20 to it. IE, if you generated 10 previously, the new value will be (10-10) + rand(0, 20) => rand(0, 20) and so on.

hope this helps

[Gunner54]

char new_rand = (old_rand - 20) + rand() % 21
old_rand = new_rand;

dont understand where i put my int... ***? old_rand? = new_rand?

packet[siz] = new_rand;

?

[sunburnt]

In that code "old_rand" is the number you generated previously. new_rand is the number you are generating currently. old_rand = new_rand implies that next time around, this time's number will be the old number.

char new_rand = (old_rand - 20) + rand() % 21
packet[siz] = new_rand;
old_rand = new_rand;