Loop Parenthesis

Forum 2005-2010 (read only) Software Syntax & Programs
1

Why are there Parenthesis after loop in Sketch? I am just starting and this bugs the shit out of me. If anyone can give me an answer it would help me alot since I sometimes get hung up on little things like that when learning something new.

2

A short-but-not-very-satisfying answer:
Treat it as an idiom. You don't have to like it, but you have to live with it as long as you are doing things the "Arduino Way."

A longer-but-actually-makes-you-learn-a-little-or-maybe-makes-you-sorry-you-asked answer:
Every Arduino sketch gets embedded in a C++ program file. The syntax shown means that the identifier loop is a function name. The function has a void return data type. The function has no parameters.

Same for setup.

Regards,

Dave

Footnote:
Consider the following sketch:

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

void loop()
{
    Serial.println("Hi");
    delay(1000);
}

Your stuff gets put into a C++ program file that looks like this:

#include "WProgram.h"
void setup();
void loop();
void setup()
{
    Serial.begin(9600);
}

void loop()
{
    Serial.println("Hi");
    delay(1000);
}

That file is compiled and linked with the necessary Arduino core files to allow the complete program to be put together in a way that the Arduino hardware can execute it.

In particular, here is the main C++ program file that will be linked to your stuff. The main() function calls some Arduino-provided initialization function, then it calls your setup function once and then repeatedly calls your loop function time after time after time...

#include <WProgram.h>

int main(void)
{
      init();

      setup();
    
      for (;;)
            loop();
        
      return 0;
}

The whole point of the Arduino developers is to let people start doing interesting things without having to learn a bunch of stuff like this at the beginning. It can be kind of frustrating for people who know (or want to know) a little C++ but can't see how the heck anything works with the "Arduino Way."

3

Thank you. This is why I love the internets.

4

Arduino-provided initialization function

Is that init function something in the Arduino core library that one could look at for educational purposes?

Lefty

5

Is that init function something in the Arduino core library

Yes. It's in "wiring.c". It starts the timers running and ensures the A/D converter is ready for business.

that one could look at for educational purposes?

Absolutely. But bring your datasheet.