Switch Function problems

Using Arduino Project Guidance
1

So i actually did this often and it worked before. But somehow i forgot and can't seem to work out whats missing...

Heres the Code

boolean Power =  false;

  switch (Second)
  {

    case 0 ... 7:
      if (Power = true) 
      {
        Serial.println("Lights OFF");
        Power = false;
        };
      break;

    case 8 ... 40:
      if (Power = false) 
      {
        Serial.println("Lights On");
        Power = true;
      };
      break;

    case 41 ... 59:
      if (Power = true) 
      {
        Serial.println("Lights OFF");
        Power = false;
        };
      break;
  }

Ive cuz out the rest of the Code cause its not relevant for this Problem. The Numbers are Seconds ranging from 0-59 (being pulled from a RTC and later replaced by Hours).

However the Serial Monitor sends Lights OFF/ON every time

I just want this function to Send the text to the Serial Monitor once it goes from 7 to 8 and from 40 to 41.

2

In your if statements, = is for assignment, == is for comparison. The if statements use comparison.

From the reference for the if structure:

Beware of accidentally using the single equal sign (e.g. if (x = 10) ). The single equal sign is the assignment operator, and sets x to 10 (puts the value 10 into the variable x). Instead use the double equal sign (e.g. if (x == 10) ), which is the comparison operator, and tests whether x is equal to 10 or not. The latter statement is only true if x equals 10, but the former statement will always be true.

This is because C++ evaluates the statement if (x=10) as follows: 10 is assigned to x (remember that the single equal sign is the (assignment operator)), so x now contains 10. Then the 'if' conditional evaluates 10, which always evaluates to TRUE, since any non-zero number evaluates to TRUE. Consequently, if (x = 10) will always evaluate to TRUE, which is not the desired result when using an 'if' statement. Additionally, the variable x will be set to 10, which is also not a desired action.

1 Like
3

Ithink you are right. I d´not why not work
Look this link:

and all if has = not ==.

RV mineirin

4

That did the trick! Thanks! ^^

so it would look like this in the end

 
  switch (Second)
  {

    case 0 ... 7:
      if (Power == true) 
      {
        Serial.println("Lights OFF");
        Power = false;
        };
      break;

    case 8 ... 40:
      if (Power == false) 
      {
        Serial.println("Lights On");
        Power = true;
      };
      break;

    case 41 ... 59:
      if (Power == true) 
      {
        Serial.println("Lights OFF");
        Power = false;
        };
      break;
  }
5

?

There isn’t a single if statement on that page, correct or not.

So where did you mean to point us at?

a7

6

@alto777 did you see it?

7

yep got it fixed now.

8

Yes, sry, I thought you were saying that the page you linked had that kind of error.

Language peobkem.

a7

9

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