hey im new to this and have just just noticed that in the two following sketches the led is named in the int in one but not the other.
in the first sketch it is not labelled in the int (nor is it called in the loop), and if i do label it in the int section the code runs no different to without it.
const int buttonPin = 2; // the number of the pushbutton pin
const int buttonPin2 = 3;
const int ledPin = 4; // the number of the LED pin
// variables will change:
int buttonState = 0; // variable for reading the pushbutton status
int buttonState2 = 0;
void setup() {
// initialize the LED pin as an output:
pinMode(ledPin, OUTPUT);
// initialize the pushbutton pin as an input:
pinMode(buttonPin, INPUT);
pinMode(buttonPin2, INPUT);
}
void loop(){
// read the state of the pushbutton value:
buttonState = digitalRead(buttonPin);
buttonState2 = digitalRead(buttonPin2);
// check if the pushbutton is pressed.
// if it is, the buttonState is HIGH:
if ( (digitalRead(2) == HIGH && digitalRead (3) == HIGH) ) {
// turn LED on:
digitalWrite(ledPin, HIGH);
}
else {
// turn LED off:
digitalWrite(ledPin, LOW);
}
}
but if i try to remove the int for the ledstate (which is called in the IF/ELSE) in the following sketch it will not compile.
const int ledPin = 13; // the number of the LED pin
// Variables will change:
int ledState = LOW; // ledState used to set the LED
long previousMillis = 0; // will store last time LED was updated// the follow variables is a long because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long interval = 1000; // interval at which to blink (milliseconds)void setup() {
// set the digital pin as output:
pinMode(ledPin, OUTPUT);
}void loop()
{
// here is where you'd put code that needs to be running all the time.// check to see if it's time to blink the LED; that is, if the
// difference between the current time and last time you blinked
// the LED is bigger than the interval at which you want to
// blink the LED.
unsigned long currentMillis = millis();if(currentMillis - previousMillis > interval) {
// save the last time you blinked the LED
previousMillis = currentMillis;// if the LED is off turn it on and vice-versa:
if (ledState == LOW)
ledState = HIGH;
else
ledState = LOW;// set the LED with the ledState of the variable:
digitalWrite(ledPin, ledState);
}
}
both codes contain an led output and a IF ELSE statement, are they just different ways of doing a very similiar thing?
my original question relates to the following two bits of code.