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Topic: error when compiling (Read 764 times) previous topic - next topic


Dec 30, 2009, 01:44 am Last Edit: Dec 30, 2009, 01:45 am by monkphin Reason: 1
Just started to really toy with an arduino I was bought for christmas, so I'm pretty new to coding on it.

I'm getting the following error when compiling the code below.

"error: expected primary-expression before '=' token"

Code: [Select]
#define RED     2    // sets the red light to pin 2
#define AMBER   3    // sets the amber light to pin 3
#define GREEN   4    // sets the green light to pin 4
#define ON = 1;       // declare what on and off mean
#define OFF = 0;      

// Array for the light control
char sequenceLength = 9;
char stateLights[]={ON, ON, OFF, OFF, ON, OFF, ON, OFF, OFF};
char stateLights[]={10000, 2000, 0, 0, 10000, 0, 3000, 0, 0};

void setup()
 pinMode(2, OUTPUT);
 pinMode(3, OUTPUT);
 pinMode(4, OUTPUT);

// code
void loop()
 char sequence = 0;  // start at element sero of all the arrays
 // and do for every light we've programmed
 while(sequence<sequenceLength))  // loop for number of sequences
   // first switch on or off the current light in the sequence
   // then if there's a delay then wait (may not need this if delay(0) works correctly)
   // next light in the sequence

The error seems to highlight
char stateLights[]={ON, ON, OFF, OFF, ON, OFF, ON, OFF, OFF};
as being the problem, but for the life of me I don't see what the issue is. Anyone have any ideas?


The problem is with the #define statements.

The compiler substitutes whatever follows the name, whenever the name occurs elsewhere.

So, this:

Code: [Select]
char stateLights[] = {ON, ON, ...


Code: [Select]
char stateLights[] = {=1;, =1;, ...

It should be obvious that that statement will not compile.

Change the #define statements to look like

Code: [Select]
#define ON 1
#define OFF 0
The art of getting good answers lies in asking good questions.


Ah, of course, thank you. Sorry I'd spent too long trying to work out what this was to see the problem, I think.

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