Arduino If Statement

Using Arduino Programming Questions
1

Hi Everyone,
I am new to Arduino Program and have a question around an if statement. I want to toggle a variable from 1 to 0 and print the results. However, when i upload the sketch it only prints out 1's. Anyone have any thoughts?

int flag = 0;
void setup() {
  Serial.begin(9600); 
}

void loop() {
    if (flag = 0){
      Serial.println(flag);
      flag = 1;
    }
    if (flag = 1){
      Serial.println(flag);
      flag = 0;
    }
}
2

= is not the same as ==

if(flag = 0) and if(flag = 1)
Change to:
if(flag == 0) and if(flag == 1)

3

If you want further information on an Arduino command or function try a Google search like this;

'Arduino reference if'

And the reference page will give you advice on how the command or function should be used.

4 
void loop() {
  Serial.println(flag);
  flag = flag ^ 1;
}
5 
if (flag = 0)      //Line-1
  {
    Serial.println(flag);
    flag = 1;                 //Line-4
  }

@OP
The above snippet is quoted from your sketch.

In Line-1, are you assigning 0 to the variable flag? Or, you are testing if the variable flag is equal to 0 or not (see Fig-1 below).

In line-4, you are surely assigning 1 to the variable flag.

operator.png
Figure-1:

operator.png

6

Also there are much other post's on this forum and other forum's, so for this couple of question i'd rather to search first before posting a question. Well you have kinda got all the information you've got now.
What also is been usefull for me and other programmer's as well are the fundamentals of the language c++.
There's an android app called soloLearn in the play store. that support's multiple languages, maybe dig into that app a bit further. i don't know if this app can be found on the ios store as well.

Best wishes, Jeff.

7

If you have a variable that will only contain 0 or 1 you should probably declare it as 'bool' or 'boolean' so the compiler can enforce that restriction for you.

It appears you are toggling between 0 and 1. You can do that with the '!' operator which does boolean inverse.

boolean flag = 0;


void setup()
{
  Serial.begin(9600);
}


void loop()
{
  Serial.println(flag);
  flag = !flag;
}

One interesting effect of how you wrote (or intended to write) your sketch:

void loop()
{
  // At this point, 'flag' is always 0

  if (flag == 0)
  {
    Serial.println(flag);
    flag = 1;
  }
  // At this point, 'flag' is always 1
  if (flag == 1)
  {
    Serial.println(flag);
    flag = 0;
  }
  // At this point, 'flag' is always 0
}

Your loop() is equivalent to:

void loop()
{
    Serial.println(0);
    Serial.println(1);
}
8

Awesome. Thank you everyone for answering this. And I am glad it was just incorrect operators.