How to use #define to assign pins in Arduino?

Question

I am trying to use #define to create a constant and define a pin, check this code

#define PIN_MICROPHONE 13;

void loop()
{
    analogRead(PIN_MICROPHONE);
}

But when trying to compile, it says this error:

: In function 'void loop()':
error: expected `)' before ';' token
error: expected primary-expression before ')' token
error: expected `;' before ')' token

How can I use #define macros to define pins?

This code compiles ok

#define PIN_MICROPHONE 13;

void loop()
{
    analogRead(13);
}

I am using Arduino 1.0.5

Arduino language is more like Java, not C (it supports class uses). — Julián Chamalé
– Julián Chamalé, Commented Jun 3, 2013 at 3:06

Moiz Raja · Accepted Answer · 2015-08-13 01:04:56Z

8

The issue is your semicolon.

#define does not require a semicolon on the end of it.

#define PIN_MICROPHONE 13
void loop()
{
    analogRead(PIN_MICROPHONE);
}

Typically the #define is a pre-compiled directive. That means before the code is compiled a find and replace is done on the text. So the IDE "saw" the code below.

void loop()
{
    analogRead(13;); //not going to work 
}

PS: I thought #defines were not encouraged in Arduino style guides.

edited Aug 13, 2015 at 1:04

Moiz Raja

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answered Jun 3, 2013 at 2:50

John b

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2 Comments

spring Over a year ago

#defines are fine ;-) arduino.cc/en/Reference/Define though apparently const is preferred.

Joe Cabezas Over a year ago

Oh my god, I feel so noob right now..., I have years of experience coding in C, C++, I'm very surprised right now, how could this happen to me... thank you John b, I believe I need to rest a little :)

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