Arduino C random LED code not turning on all the LEDs - c

Question

I'm coding with the Arduino Uno software and have ran into a problem. I'm trying to turn 8 LEDs on in a random order and then turn them all off at once. My problem is that the LEDs would turn on the same ones multiple times which in the end would not turn them all on. This makes the circuit not give the effect that I'm looking for. I've been working to fix the problem for about two hours and have tried many fixes which haven't worked. Here's the code that I'm working with:
void randomLED()
{
int i;
int index;
int delayTime;
int tracker;
int ledPin1 = ledPins[0];
int ledPin2 = ledPins[1];
int ledPin3 = ledPins[2];
int ledPin4 = ledPins[3];
int ledPin5 = ledPins[4];
int ledPin6 = ledPins[5];
int ledPin7 = ledPins[6];
int ledPin8 = ledPins[7];
boolean ledPinOne = digitalRead(ledPin1);
boolean ledPinTwo = digitalRead(ledPin2);
boolean ledPinThree = digitalRead(ledPin3);
boolean ledPinFour = digitalRead(ledPin4);
boolean ledPinFive = digitalRead(ledPin5);
boolean ledPinSix = digitalRead(ledPin6);
boolean ledPinSeven = digitalRead(ledPin7);
boolean ledPinEight = digitalRead(ledPin8);
for (i = 0; i < 8; i++) {
bailout:
index = random(8); // pick a random number between 0 and 7
if (ledPinOne != HIGH && index == 0 || ledPinTwo != HIGH && index == 1 || ledPinThree != HIGH && index == 2 || ledPinFour != HIGH && index == 3 || ledPinFive != HIGH && index == 4 || ledPinSix != HIGH && index == 5 || ledPinSeven != HIGH && index == 6 || ledPinEight != HIGH && index == 7){
digitalWrite(ledPins[index], HIGH); // turn LED on
}
delay(100); // pause to slow down
}
delay(1000);
for (i = 0; i < 8; i++){
digitalWrite(ledPins[i], LOW);
}
}
I have a large if statement because I needed to have separate conditions for each LED to turn on. These condition were needed because the random number generator would turn on the same LEDs twice which I didn't want. I was hoping that putting all of these conditions in and if statement would make the LEDs act how I wanted. I've tried changing the == and != in the if statement to every combination and it still didn't work. I'm hoping I can find and answer to my problem here that'll fix my problem.

Answer 1

There are multiple problems with your code. You are picking 8 random numbers because you want to have all 8 LEDs lit at the end, but what if you get the same number twice? So you have to somehow make sure that you pick a number that corresponds to a LED that is not already lit. Another problem with your code is that you read each LED pin only once, outside the loop. So when you are checking each pin in your large if-statement the values are not up to date.
Here is a quick but bad way of solving both these issues:
int numberOfLEDsLit = 0;
while (numberOfLEDsLit < 8) {
int index = random(8);
int ledLit = digitalRead(ledPins[index]);
if (ledLit == LOW) {
digitalWrite(ledPinds[index], HIGH);
numberOfLEDsLit++;
}
}
Basically you pick a random led, if it is not lit then light it otherwise do nothing. Continue until all 8 LEDs are lit.

Answer 2

Taking a look at the reference for random()
If it is important for a sequence of values generated by random() to differ, on subsequent executions of a sketch, use randomSeed() to initialize the random number generator with a fairly random input, such as analogRead() on an unconnected pin.
So you need to call randomSeed(seed) just before your random() call if you want the sequences to be different on each run of the program.