[Solved] Inconsistent error in syntax

Firmware
1

Hey!

I’m getting the weirdest error in my code, and I can’t seem to see what I’m missing!

void clickBtn() {
  if (!activity) {
    if (safe) System.enterSafeMode();
    else if (listen) WiFi.listen();
    else startActivity();
  } else stopActivity();
}

This little snippet (lines 265-271) works just fine, while as this one:

void clickBtn() {
  if (!activity) {
    if (safe) System.enterSafeMode();
    else if (listen) {
      WiFi.listen();
    } else startActivity();
  } else stopActivity();
}

Doesn’t work and gives me this error:

xxxxxxxxxxxxx.cpp:10:1: error: expected unqualified-id before 'else'
 else if (listen);
 ^

Thoughts?

2

This is a bug in the Wiring preprocessor. It’s what allows Arudino shortcuts like not including forward declaration of functions. This code disables the preprocessor and compiles without error with your clickBtn unchanged:

#pragma SPARK_NO_PREPROCESSOR
#include "Particle.h"

bool activity = false;
bool safe = false;
bool listen = false;

void clickBtn(); // forward declaration

void setup() {
}

void loop() {
}

void startActivity() {
}

void stopActivity() {  
}

void clickBtn() {
  if (!activity) {
    if (safe) System.enterSafeMode();
    else if (listen) {
      WiFi.listen();
    } else startActivity();
  } else stopActivity();
}
3

Cool! Thanks! So I forward declared every single one of the functions and then it worked! Seems like a bit of a hassle though, any idea whether or not that bug is going to be fixed? And what ‘activated’ the bug exactly?

4

The bug in the preprocessor is usually triggered by if statements that do not have curly braces {} around the actions. In your case you have if (safe) System.enterSafeMode();.

If you just get in the habit of always using curly braces, I think you will find that the problem goes away without turning the preprocessor off.

5

Sorry, I forgot to post the alternate way to fix this: adding a set of curly brackets where the else if clause is like this:

void clickBtn() {
  if (!activity) {
    if (safe) System.enterSafeMode();
    else {
        if (listen) {
            WiFi.listen();
        } else startActivity();
    }
  } else stopActivity();
}
1 Like
6

But I tried that as well! Had curly brackets behind every single if statement, but it didn’t help at all, that’s what threw me off.

7

Wow, totally forgot to answer you, but I tried that other way you posted, and both ways worked just fine. Bit of a workaround, though, seems unnecessary! Anyways, thank you so much!

Also, that first solution you offered only worked if I forward declared every single function before setup.