Arduino Smoothing example failing to compile.

G

gbernal

Well-known member
Hello everyone,

This is my first post here, I hope this is the right place to bring up this issues.
I'm new Teensy adaptor and fairly new to c++ so please forgive any ignorance that I might show.

I'm trying to load the smoothing example that comes with arduino to Teensy 3.1, and I get the following error when compiling.
index(const char*, int)'
sketch_apr06a.ino: In function 'void loop()':
sketch_apr06a:48: error: invalid types 'int [10][char*(const char*, int)]' for array subscript
sketch_apr06a:50: error: invalid types 'int [10][char*(const char*, int)]' for array subscript
sketch_apr06a:52: error: invalid types 'int [10][char*(const char*, int)]' for array subscript
sketch_apr06a:54: error: assignment of function 'char* index(const char*, int)'
sketch_apr06a:54: error: cannot convert 'char* (*)(const char*, int)' to 'char*(const char*, int)' in assignment
sketch_apr06a:57: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
sketch_apr06a:59: error: assignment of function 'char* index(const char*, int)'
sketch_apr06a:59: error: cannot convert 'int' to 'char*(const char*, int)' in assignment

This program will be fundament I think for what I'm trying to do, which is collect biosignals using an EMG.
I will really appreciate if someone could give some advice as how to move forward.

Thanks in advanced.
 
Sorry, Here it is

Code: 
/*

  Smoothing

  Reads repeatedly from an analog input, calculating a running average
  and printing it to the computer.  Keeps ten readings in an array and 
  continually averages them.
  
  The circuit:
    * Analog sensor (potentiometer will do) attached to analog input 0

  Created 22 April 2007
  By David A. Mellis  <dam@mellis.org>
  modified 9 Apr 2012
  by Tom Igoe
  http://www.arduino.cc/en/Tutorial/Smoothing
  
  This example code is in the public domain.


*/


// Define the number of samples to keep track of.  The higher the number,
// the more the readings will be smoothed, but the slower the output will
// respond to the input.  Using a constant rather than a normal variable lets
// use this value to determine the size of the readings array.
const int numReadings = 10;

int readings[numReadings];      // the readings from the analog input
int index = 0;                  // the index of the current reading
int total = 0;                  // the running total
int average = 0;                // the average

int inputPin = A0;

void setup()
{
  // initialize serial communication with computer:
  Serial.begin(9600);                   
  // initialize all the readings to 0: 
  for (int thisReading = 0; thisReading < numReadings; thisReading++)
    readings[thisReading] = 0;          
}

void loop() {
  // subtract the last reading:
  total= total - readings[index];         
  // read from the sensor:  
  readings[index] = analogRead(inputPin); 
  // add the reading to the total:
  total= total + readings[index];       
  // advance to the next position in the array:  
  index = index + 1;                    

  // if we're at the end of the array...
  if (index >= numReadings)              
    // ...wrap around to the beginning: 
    index = 0;                           

  // calculate the average:
  average = total / numReadings;         
  // send it to the computer as ASCII digits
  Serial.println(average);   
  delay(1);        // delay in between reads for stability            
}
 
Great!, Thank you for the quick reply!. I'm very much exited to use this platform in this and future projects. :)
 
Yikes, hard to believe this issue hasn't come up before. Or maybe it has, but I just don't recall?

Looks like newlib defines index() and rindex() as string manipulation functions. That's not in avr-libc, but they are pretty standard in C libraries on traditional compilers.

The same problem happens with Arduino Due, so I've filed a bug report with Arduino.

https://github.com/arduino/Arduino/issues/1993

Maybe the best thing for the moment would be to watch what Arduino does on this?

I'm leaning towards tweaking that header file to comment out the index() definition....
 
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