Compiler error

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

Hello
I've got a problem which i think is related to a scope issue. But i'm completely blank and have tried a lot of different stuff to get rid of the compiler error. Here is the code of a simple state machine:

/* statemachine */

enum {ms_idle,ms_start,ms_stop};

typedef struct{
 int state,oldstate;
 int time;
}smtype;

void sm_update(smtype *p);

smtype mission;

void setup(){
  Serial.begin(9600);
  mission.state=ms_idle;
}

void loop(){
  sm_update(&mission);
  switch(mission.state){
    case ms_idle:
    Serial.print("state idle");
    delay(5000);
    mission.state=ms_start;
    break;
        
    case ms_start:
    Serial.print("state start");
    delay(5000);
    mission.state=ms_stop;
    break;
    
    case ms_stop:
    Serial.print("state stop");
    delay(5000);
    break;
    
  }      
}

void sm_update(smtype *p){
  if (p->state!=p->oldstate){
       p->time=0;
       p->oldstate=p->state;
   }
   else {
     p->time++;
   }
}

This results in a compiler error:
statemachine:1: error: variable or field 'sm_update' declared void
statemachine:1: error: 'smtype' was not declared in this scope
statemachine:1: error: 'p' was not declared in this scope

The compiler is complaining over the void sm_update(smtype *p)
function.

Hope someone can give me a clue what's wrong in this code.

Cheers

2

I think you're right about the scope problem. If I add a scope resolution operator to the two function headers, the code compiles fine:

void sm_update(::smtype *p)

I don't know enough about the Arduino IDE to explain why, though. Maybe your free function gets wrapped up in some namespace?

3

There's something that the Arduino compiler does not like about your structure definition. I changed it to

struct st{
 int state,oldstate;
 int time;
};

Then changed all occurrences of smtype to struct st, and it compiled.

4

try to define the typedef in a separate .h file as the IDE autogenerates function prototypes before the definition of smtype.

5

Thanks for the quick replies :slight_smile: