Function pointer array, passing values defined in array

Question

I'm trying to define an array of function pointers, where each function contains an int parameter. I'm also trying to set the value of that int parameter in the array declaration

So I have a TIMED_TASK struct, that will hold the function pointer and value I want to pass

typedef struct
{
   void (*proc)(int);  
   int delayMsec;     
} TIMED_TASK;

Then I have an array of TIMED_TASKs like this

static const TIMED_TASK attractSequence[] =
{
    { LightsOn, 1000 },
    { LightsOff, 500 },
    { EndSequence, 0 }
};

And I'd like it to call each of those functions in turn, passing the delay value to each function. This is where I expect I have the wrong syntax (I'm still learning C). I seemingly don't hit my LightsOn() routine at all

void loop() // It's an arduino project :)
{
  attractSequence[sequence];
  sequence++;
}

void LightsOn(int pause)
{
  // I do not hit this routine for some reason?
  Serial.print("LIGHTS ON"); 
  Serial.print(pause);
}

void LightsOff(int pause)
{
  Serial.print("LIGHTS OFF");
  Serial.print(pause);
}

It's entirely possible I'm taking the wrong approach here, but hopefully you can see what I'm trying to achieve. Any advice very welcome!

Are you sure this is straight up C? This looks like an embedded dialect like the arduino language. — alexgolec
– alexgolec, Commented Sep 25, 2015 at 21:37
Correct, it's an arduino project. But I believe the syntax should be the same as C? — PaulG
– PaulG, Commented Sep 25, 2015 at 21:37
It's not, Serial.print(pause) is invalid c, not entirely invalid but as it is in your code it seems to be. Also, you are never calling the function through the pointer, where do i expect it to be called in the posted code? — Iharob Al Asimi
– Iharob Al Asimi, Commented Sep 25, 2015 at 21:37

R Sahu · Accepted Answer · 2015-09-25 21:39:23Z

5

If you want to go through each item of attractSequence only once, you can use:

void loop()
{
   int count = sizeof(attractSequence)/sizeof(attractSequence[0]);
   for (int i = 0; i < count; ++i )
   {
     attractSequence[i].proc(attractSequence[i].delayMsec);
   }
}

answered Sep 25, 2015 at 21:39

R Sahu

207k15 gold badges168 silver badges291 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

PaulG Over a year ago

Fantastic! Thank you. The syntax I needed was attractSequence[sequence].proc(attractSequence[sequence].delayMsec). Makes perfect sense now that I see it

Collectives™ on Stack Overflow

Function pointer array, passing values defined in array

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related