Toying with variables

Using Arduino Programming Questions
1

Hello! I was wondering how to use a short and where to use it. The plan was to have a very basic setup where I have three LEDs and a button. The LEDs are controlled via a short deciding which LED to turn on (if 1 turn on red and turn off previous, and so on) When pressed the button would add one to the short (which starts at 1); when the short is greater than 3 it is put back to one. I was wondering am I using this right and if so how to use it, or even if I should be using a short. Thank you for your time and support of a fresh baby to the beautiful world of Arduino! :slight_smile:

int Green = 5;
int Yellow = 6;
int Red = 7;
int Button = 8;
short lightNumber = 1;
void setup() {
pinMode(Button, INPUT);
pinMode(Green, OUTPUT);
pinMode(Yellow, OUTPUT);
pinMode(Red, OUTPUT);
}
void loop() {
  if(digitalRead(Button) == HIGH)
  {
    digitalWrite(lightNumber +1) 
  }
 else
 {
  digitalWrite(lightNumber, + 1);
 }
}
2

"short" is just another name for "int", so there is no difference between any of these:

int lightNumber = 1;
short int lightNumber = 1;
short lightNumber = 1;

"long" however, is different to "int".

3

It appears you need to go through some of the basic examples that come with the IDE.
Once you master the basics, proceed with your project.

4

Hello and welcome,

  • For most arduinos, short is the same thing as int: a 16 bits, signed variable. Do you need a 16 bits, signed variable to store a number between 1 and 3 ? No, 3 can be stored in 2 bits, so you can use the smallest unsigned variable type, which is the byte ( or: uint8_t ).

  • digitalWrite takes 2 parameters: a pin number and the state to be written to that pin.

  • You have to assign a new value to lightNumber, if you want it to increase.

lightNumber = lightnumber + 1;

, or you can also use the increment operator

lightNumber++;

  • You also have to use a debouncing method and, if you want to increment by 1 every time you press the button, you also need a state change detection method. You can also use a button library, which will do all the hard work for you. This library also contains an example that is almost exactly what you want to do.. :wink:

  • To constraint the variable between 1 and 3, just check (after increment) if the variable equals 3, in which case you set it to 1.

5

For your coding, this example should get you a long way there:

6

Thank you for all the help.