Problems Generating Random Numbers

Projects Programming
1

hi guys
im trying to generate three different, random, numbers per cycle of the code however i don't understand why i'm getting the outputs i'm getting. To my mind all three of the "TESTs" should give me the same values. instead thy r all different and all unusable due to duplicate values.
Im really more interested in knowing why it is not working as i think it should than simply being told how i should have written the code.

anyway, the questions id like answered are:

  1. why dose "TEST 1" give the same value for the 1st & 2nd variable?
  2. why dose "TEST 2" give the same value all variable?
  3. why is the 1st variable in "TEST 2" always "0"?
  4. why cant i combine line 15 & 16? like so: "ran[r] = random(0,255);" if i do combine them, i get some crazy numbers!

thanks for the help

int r; //couter forloop random number genereator
int ran[]={};// array containing 3 random numbers
int RedBri[] = {}; 
int GreenBri[]={}; 
int BlueBri[]={}; 
int prox;

void setup() {
Serial.begin(9600); 
randomSeed(analogRead(0)); // generater random value using noise from the analog read pin
}

void loop() {
for(r=0; r<=2; r++){ //loop to generater 3 random numbers
prox = random(0,255);// generate random number
ran[r] = prox;  // stor random number in array
}

RedBri[0]    = ran[0];  // assign random numbers to neopixel value array
GreenBri[0]  = ran[1];  
BlueBri[0]   = ran[2];

Serial.println("     test 1");
Serial.println(ran[0]);         //********TEST 1*********
Serial.println(ran[1]);         //********TEST 1 ********
Serial.println(ran[2]);         //********TEST 1*********

Serial.println("     test 2");
Serial.println(RedBri[0]);     //********TEST 2*********
Serial.println(GreenBri[0]);   //********TEST 2 ********
Serial.println(BlueBri[0]);    //********TEST 2*********



Serial.println("     test 3"); //********TEST 3*********
for(r=0; r<=2; r++){           
Serial.println(ran[r]);
}

Serial.println(" ");
delay (1000);
}
3

ah! it was that simple! :slight_smile: this is this the problem with being a noob :frowning:

many thanks Delta_G

4

SavageRodent:
ah! it was that simple! :slight_smile: this is this the problem with being a noob :frowning:

many thanks Delta_G

You know that array variables WILL get the proper number of elements if they are specified ahead of time... like this:

int array[] = { 10, 20, 30, 40, 50 }; // this is now "array[5]" (right)

int array[] = { }; // this is now "array[0]" (useless)

int array[5] = { }; // this is now an empty "array[5]" (right)