Arduino problems with array - c

Question

Hi I am working on a project lighting my house lights using an Arduino.
I have it working in a basic form, now I want to store the previous state of the light switch. I am using an array that stores the current state of the switch so it can be compared on the next loop. I have 7 switches, I have created it so one switch has the ability to turn on many lights, if required.
I need to store the previous state as the next part is to introduce web control the test project for this is already written
The strange thing is zones 7/8 work perfect. the other zones turn on, but don't turn off. When I turn on another switch a light may go off if it's switch is in the off position.
If I remove the condition for the previous state check all switches perfectly fine.
const int zone2[] = {8,13,0};
const int zone3[] = {11,0};
const int zone4[] = {7,0};
const int zone5[] = {9,0};
const int zone6[] = {12,0};
const int zone7[] = {6,0};
const int zone8[] = {14,0};
const int * zones[]={zone2,zone3,zone4,zone5,zone6,zone7,zone8};
int buttonState[] = {0,0}; // variable for reading the pushbutton status
int previousState[]={0,0,0,0,0,0,0,0}; // array for holding the previous state of the input button
void setup()
{
//initialize the output pins that will control lights
pinMode(6,OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9,OUTPUT);
pinMode(11, OUTPUT);
pinMode(12, OUTPUT);
pinMode(13,OUTPUT);
pinMode(14,OUTPUT);
// initialize the pushbutton pin as an input:
//set all light switches to the same block ie pins 30 - 35
byte i;
//this loop sets all the 30-35pins as inputs
for (i=30;i< 37;i++) {
pinMode(i, INPUT);
digitalWrite(i,HIGH); // this makes it connect to the internal resistor
}
}
void loop()
{
int arrayPosition;
for (int z = 0; z < 7; ++z)//zero based array needs to be as many as there are zones!!!
{
buttonState[z] = digitalRead(z+30);
for (arrayPosition = 0;zones[z][arrayPosition] ; arrayPosition++)
{
if ((buttonState[z] == HIGH) ) && (previousState[z] == LOW )) {
// turn LED on:
digitalWrite(zones[z][arrayPosition],HIGH);
}
else if ((buttonState[z] == LOW) && (previousState[z] == HIGH )) {
// turn LED off;
digitalWrite(zones[z][arrayPosition],LOW);
}
}
//each light assigned to the zone has been turned on or off, now set previousstate
//the statement is here the inner loop has finsihed turning lights on or off that belong to that zone
previousState[z] = buttonState[z];
}
}

Answer 1

You allocate two elements to the array buttonState, but you are accessing seven:
[…]
int buttonState[] = {0,0};
[…]
for (int z = 0; z < 7; ++z)
{
buttonState[z] = digitalRead(z+30);
[…]
You should increase the number of elements in the buttonState array to be as many as you actually need.
It might be better to define the size of the arrays at a single place:
#define NUM_ZONES (7)
[…]
const int * zones[NUM_ZONES]={zone2,zone3,zone4,zone5,zone6,zone7,zone8};
int buttonState[NUM_ZONES] = {0,0,0,0,0,0,0};
int previousState[NUM_ZONES]={0,0,0,0,0,0,0};
[…]
for (int z = 0; z < NUM_ZONES; ++z)
[…]
This will also reveal that your previousState array is larger than needed (the compiler will complain that you have too many initialisers for that array). It is then important to re-use that constant everywhere instead of writing the magic number 7.