[GH-ISSUE #172] AutoConnectWithFSParameters issue with #include ordering #136

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opened 2026-02-28 01:23:38 +03:00 by kerem · 2 comments

kerem commented

2026-02-28 01:23:38 +03:00

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Originally created by @vrolijkegast on GitHub (May 16, 2016).
Original GitHub issue: https://github.com/tzapu/WiFiManager/issues/172

I was unable to compile the AutoConnectWithFSParameters example

The error message was:
/ .... / Polyfills/isNaN.hpp:29:17: error: 'isnan' was not declared in this scope
return isnan(x);

After investigation, I found out that there was a conflict between <WiFiManager.h> and <ArduinoJson.h>. I looks like WiFiManager does an 'undef' of isnan. Maybe it somehow includes cmath.h ? When I reordered the include statements, it compiles without issues. I stopped investigating after that.
The code now looks like this:

// this needs to be included BEFORE <WiFiManager.h>

include <ArduinoJson.h> //https://github.com/bblanchon/ArduinoJson

//needed for library

include <DNSServer.h>

include <ESP8266WebServer.h>

include <WiFiManager.h> //https://github.com/tzapu/WiFiManager

Since it took me quite some time, I thought I should share it.
I am using ArduinoIDE 1.6.8. on Ubuntu Linux.
I compile the code for a 'Wemos D1 mini' (based on the ESP8266)

Originally created by @vrolijkegast on GitHub (May 16, 2016). Original GitHub issue: https://github.com/tzapu/WiFiManager/issues/172 I was unable to compile the AutoConnectWithFSParameters example The error message was: <ArduinoJson-path>/ .... / Polyfills/isNaN.hpp:29:17: error: 'isnan' was not declared in this scope return isnan(x); After investigation, I found out that there was a conflict between <WiFiManager.h> and <ArduinoJson.h>. I looks like WiFiManager does an 'undef' of isnan. Maybe it somehow includes cmath.h ? When I reordered the include statements, it compiles without issues. I stopped investigating after that. The code now looks like this: // this needs to be included BEFORE <WiFiManager.h> # include <ArduinoJson.h> //https://github.com/bblanchon/ArduinoJson //needed for library # include <DNSServer.h> # include <ESP8266WebServer.h> # include <WiFiManager.h> //https://github.com/tzapu/WiFiManager Since it took me quite some time, I thought I should share it. I am using ArduinoIDE 1.6.8. on Ubuntu Linux. I compile the code for a 'Wemos D1 mini' (based on the ESP8266)

kerem closed this issue

2026-02-28 01:23:38 +03:00

kerem commented

2026-02-28 01:23:38 +03:00

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@kentaylor commented on GitHub (May 16, 2016):

That suggests a feather in the cap of @battika for getting the order this way in his version at https://github.com/kentaylor/WiFiManager/blob/master/examples/ConfigOnSwitchFS/ConfigOnSwitchFS.ino

@kentaylor commented on GitHub (May 16, 2016): That suggests a [feather in the cap ](https://goo.gl/FygtbL) of @battika for getting the order this way in his version at https://github.com/kentaylor/WiFiManager/blob/master/examples/ConfigOnSwitchFS/ConfigOnSwitchFS.ino

kerem commented

2026-02-28 01:23:38 +03:00

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@tzapu commented on GitHub (Jun 2, 2016):

hi, just to let you know that the undefs and everything related to that has been reverted in the latest version

thanks for reporting and using ;)
reopen if still an issue

@tzapu commented on GitHub (Jun 2, 2016): hi, just to let you know that the undefs and everything related to that has been reverted in the latest version thanks for reporting and using ;) reopen if still an issue