max() and min() functions not available

Official Hardware Classic Zero
1

Hello Arduino Zero Forum.

In attempting to test an Adafruit 2.8" TFT with Capacitive Touchpad, I discovered that LadyAda's graphicstest.ino example would not compile. Seems that it can't see the min() and max() functions.
I am using Arduino IDE revision 1.6.5

I boiled it down to a simple example - adding some math to the standard "blink" example.

// the setup function runs once when you press reset or power the board
void setup() {
int x,y,z;

// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);

x = 10;
y = 20;
z = min(x, y);
}

// the loop function runs over and over again forever
void loop() {
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}

The error message is as follows:

Arduino: 1.6.5 (Windows 7), Board: "Arduino Zero (Programming Port)"

Build options changed, rebuilding all

sketch_jun19b.ino: In function 'void setup()':
sketch_jun19b:10: error: 'min' was not declared in this scope
'min' was not declared in this scope

The exact same code compiles and runs properly on an Arduino Uno.

Cheers,
Jim Lynch :confused:

2

Really strange. Even redefining the max macro in the program did not work for me. I tried the following:

#undef max
#define max(a,b) ((a)>(b)?(a):(b))
void setup()
{
  int z = max(10,5);
}

Still received an error that max was not defined. I looked and it is defined in the wiring_constant.h file in the SAMD core directory.

It's a bug but I don't know why. As a temp solution you could try the following:

inline int max(int a,int b) {return ((a)>(b)?(a):(b)); }
void setup()
{
  int z = max(10,5);
}
3

Thanks Denbo for verifying my observation about the built-in min() and max() functions.

Your work-around works for the simple case, but to get LadyAda's graphics library to compile correctly would require modification of her graphics subroutines - it would be more prudent for me to wait.

Is posting to this forum sufficient to alert the Arduino Zero team about this bug?

Cheers, Jim Lynch

4

I believe you can post bugs here Issues · arduino/ArduinoCore-samd · GitHub

5

By the way it will work for the Adafruit_GFX library but it must be in the library itself after the include to Arduino.h. You can add in the last 3 lines of code as follows in Adafruit_GFX.h

#ifndef _ADAFRUIT_GFX_H
#define _ADAFRUIT_GFX_H

#if ARDUINO >= 100
 #include "Arduino.h"
 #include "Print.h"
#else
 #include "WProgram.h"
#endif

// add in the next 3 lines
#undef min
inline int min(int a, int b) { return ((a)<(b) ? (a) : (b)); }
inline double min(double a, double b) { return ((a)<(b) ? (a) : (b)); }
6

Denbo:
I believe you can post bugs here Issues · arduino/ArduinoCore-samd · GitHub

I've added the issue.

Wayne

7

It's a really weird bug, it seems that if "max" or "min" are defined, simply including <stdint.h> will make them disappear (undefine in some way? I coulnd't find where this happens exactly in stdint.h....)

BTW I've opened a pull request with a fix here:

if someone could try it before merging that would be wonderful.

8

cmaglie:
if someone could try it before merging that would be wonderful.

I tried making the changes manually and they seem to fix the problem. At least, statements like this now compile:

 int temp = min(1,2);
  int tmp2 = max(2,4);

Wayne

9

May I ask when the fix for this issue will make it into the ARDUINO SOFTWARE
HOURLY BUILDS in the download section?

10

We are setting up also the hourly build... you have to be a bit patient!

11

Not to worry - I raised two teenagers by myself. Patience is my best virtue.

12

Thanks!!!

13

The nightly builds are now available!

Here the instructions:

enjoy!

14

OK, that worked - LadyAda's LCD displaytest nowruns properly for me.

Hope the fix gets into an official release soon. :slight_smile: