Rand or Random for random numbers?

Firmware
1

In arduino, it’s random(min, max), but I was typing in the Spark Build and it highlighted just rand. Is that the built-in function? I saw some examples using function like:

int random(int max) {
  return random(0, max);
}

int random(int minVal, int maxVal)
{
  // int rand(void); included by default from newlib
  return rand() % (maxVal-minVal+1) + minVal;
}

I wonder why do we have wrap the rand() function that way?

2

You won’t have to do this for much longer :slight_smile:

1 Like
3

Nice! Looking fwd to!

4

@metaculus, having @mdma on the Spark Team rocks! Until that change makes it to production, you can look at @kennethlimcp's repo for another topic (spark_wiring_random.cpp & .h) for files you can use. :smile:

2 Likes
5

Thanks, but I can’t take the credit for this one, it was @zachary who did the lion’s share of the work here. I just added some unit tests.

Equally exciting is that the firmware can how get a random seed from the cloud (from a cryptographically secure source) so sequences start from a very randomized seed.

1 Like
6

I’m guessing the work from this is in production now? I’m hitting the following error if I try to use randomSeed(analogRead(A0));

blink.cpp:1:11: error: expected constructor, destructor, or type conversion before '(' token
7

The surrounding code of your suspected trouble line would be good.

8

as @ScruffR says, the error report says that you are calling this on line 1 of the blink.cpp which is not likely to work. Did you mean to call it in setup() or loop() or some other function instead?

9

Ah, didn’t know this had to be inside of a function, originally had the following just to isolate the issue. Looks like throwing it inside setup or loop works fine.

randomSeed(analogRead(A0));

void setup() {}
void loop() {}