EXPECTED INITIALIZER BEFORE 'IF'

Projects Programming
1

Hi. I have been attempting some basic if else else if coding and I seem to be doing something wrong. I think it might have to do with the analogPin or threshold but I am not totally sure what those are or how to include them. THANK YOU!

const int ledPin = 13;
void setup()
{
pinMode(ledPin,OUTPUT);
}
void loop()
if (ledPin = LOW)
{
digitalWrite(ledPin,OUTPUT);
}
else
{
digitalWrite(ledPin,LOW);
}

Arduino: 1.6.5 (Mac OS X), Board: "Arduino/Genuino Uno"

elseif:7: error: expected initializer before 'if'
elseif:11: error: expected unqualified-id before 'else'
expected initializer before 'if'

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2

Malformed loop function, no { }, = in place of == used. OUTPUT in place of HIGH should work, but is at least bad style.

const int ledPin = 13;
void setup()
{
  pinMode(ledPin, OUTPUT);
}
void loop() {
  if (ledPin == LOW)
  {
    digitalWrite(ledPin, HIGH);
  }
  else
  {
    digitalWrite(ledPin, LOW);
  }
}
3

Thank you so much! It worked

4

What do you mean:

  if (ledPin == LOW)

since ledPin always equals 13? LOW always equals zero. When does 13=0?

5

I am not totally sure myself as I have started coding and arduino itself recently, but I thought that i was saying that if pin 13, or the LED was off, or LOW, to turn it on. Feel free to correct me. Also, when I updated the code to my arduino uno board, it always uses the TX and RX really quickly, then does the command. Thx

6

You're checking if LedPin is equal to LOW (which is actually just a constant defined as 0). LedPin is 13, not 0, so that will never be true. That's equivilent to if (13 == 0)

You probably meant to read the value on pin 13, and compare THAT to LOW:

if (digitalRead(LedPin)==13)

7 
const int ledPin = 13;
void setup()
{
  pinMode(ledPin, OUTPUT);
}
void loop() {
  if (digitalRead(ledPin) == LOW)
  {
    digitalWrite(ledPin, HIGH);
  }
  else
  {
    digitalWrite(ledPin, LOW);
  }
}
8

Or even:

void setup()
{
  pinMode(LED_BUILTIN, OUTPUT);
}
void loop() {
digitalWrite( LED_BUILTIN, !digitalRead(LED_BUILTIN) );
}
9

Thank you, you three. That all helped and I will build off what you said.