Arduino is C++

by Peter Stevenson on March 16, 2022 under programming

3 minute read

Is Arduino C++?

A friend asked the following questions which provoked some thought:

> Is Arduino its own language?
> Is Arduino based on Processing, Java, C++ or C?
> Are Arduino sketches/programs classed as a firmware?

TLDR

More of a domain language.

avr-gcc which includes avr-g++

So Ardunio (arduino-1.8.8) is C++ 11 (-std=gnu++11) but without any standard libraries so it can have optimised versions that consume less memory and are safer from leaks.

Yes an Arduino program/sketch would qualify as a firmware.

C++ IDE

Non C++ IDE

Arduino IDE 1.8.8
https://marketplace.visualstudio.com/items?itemName=vsciot-vscode.vscode-arduino
Arduino IDE version 2.0.0-beta.3

arduino-is-cpp.ino

void setup() {
  Serial.begin(9600);
  while(!Serial){}
  Serial.println(__cplusplus);
}

void loop() {}

Output

Verbose compiler output

/home/peter/downloads/arduino-1.8.8/arduino-builder -dump-prefs -logger=machine -hardware /home/peter/downloads/arduino-1.8.8/hardware -tools /home/peter/downloads/arduino-1.8.8/tools-builder -tools /home/peter/downloads/arduino-1.8.8/hardware/tools/avr -built-in-libraries /home/peter/downloads/arduino-1.8.8/libraries -libraries /home/peter/Arduino/libraries -fqbn=arduino:avr:uno -vid-pid=0X2341_0X0043 -ide-version=10808 -build-path /tmp/arduino_build_342783 -warnings=none -build-cache /tmp/arduino_cache_309119 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.avr-gcc.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avr-gcc-5.4.0-atmel3.6.1-arduino2.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA-1.2.1.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude-6.3.0-arduino14.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -verbose /home/peter/downloads/sketch_may15a/sketch_may15a.ino
/home/peter/downloads/arduino-1.8.8/arduino-builder -compile -logger=machine -hardware /home/peter/downloads/arduino-1.8.8/hardware -tools /home/peter/downloads/arduino-1.8.8/tools-builder -tools /home/peter/downloads/arduino-1.8.8/hardware/tools/avr -built-in-libraries /home/peter/downloads/arduino-1.8.8/libraries -libraries /home/peter/Arduino/libraries -fqbn=arduino:avr:uno -vid-pid=0X2341_0X0043 -ide-version=10808 -build-path /tmp/arduino_build_342783 -warnings=none -build-cache /tmp/arduino_cache_309119 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.avr-gcc.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avr-gcc-5.4.0-atmel3.6.1-arduino2.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA-1.2.1.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude-6.3.0-arduino14.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -verbose /home/peter/downloads/sketch_may15a/sketch_may15a.ino
Using board 'uno' from platform in folder: /home/peter/downloads/arduino-1.8.8/hardware/arduino/avr
Using core 'arduino' from platform in folder: /home/peter/downloads/arduino-1.8.8/hardware/arduino/avr
Detecting libraries used...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-g++ -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10808 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/cores/arduino -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/variants/standard /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp -o /dev/null
Generating function prototypes...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-g++ -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10808 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/cores/arduino -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/variants/standard /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp -o /tmp/arduino_build_342783/preproc/ctags_target_for_gcc_minus_e.cpp
/home/peter/downloads/arduino-1.8.8/tools-builder/ctags/5.8-arduino11/ctags -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives /tmp/arduino_build_342783/preproc/ctags_target_for_gcc_minus_e.cpp
Compiling sketch...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-g++ -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -MMD -flto -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10808 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/cores/arduino -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/variants/standard /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp -o /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp.o
Compiling libraries...
Compiling core...
Using precompiled core: /tmp/arduino_cache_309119/core/core_arduino_avr_uno_dbe74caced8262d937c72ad4123d41cb.a
Linking everything together...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-gcc -w -Os -g -flto -fuse-linker-plugin -Wl,--gc-sections -mmcu=atmega328p -o /tmp/arduino_build_342783/sketch_may15a.ino.elf /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp.o /tmp/arduino_build_342783/../arduino_cache_309119/core/core_arduino_avr_uno_dbe74caced8262d937c72ad4123d41cb.a -L/tmp/arduino_build_342783 -lm
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-objcopy -O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 /tmp/arduino_build_342783/sketch_may15a.ino.elf /tmp/arduino_build_342783/sketch_may15a.ino.eep
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-objcopy -O ihex -R .eeprom /tmp/arduino_build_342783/sketch_may15a.ino.elf /tmp/arduino_build_342783/sketch_may15a.ino.hex
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-size -A /tmp/arduino_build_342783/sketch_may15a.ino.elf
Sketch uses 1634 bytes (5%) of program storage space. Maximum is 32256 bytes.
Global variables use 188 bytes (9%) of dynamic memory, leaving 1860 bytes for local variables. Maximum is 2048 bytes.

Research links

Arduino Forum - Changing/Finding Out The C++ Compiler Version
Wikipedia - Wiring (development platform)
- More of a domain language.
- > The Wiring IDE includes a C/C++ library called “Wiring”, which makes common input/output operations much easier. Wiring programs are written in C++.
Wikipedia - Processing (programming language)
- > Processing has spawned another project, Wiring, which uses the Processing IDE with a collection of libraries written in the C++ language
- This is where the confusion comes in around Java. However this is only relevant to the Processing language which isn’t what Arduino uses.
  - > Written in Java, GLSL, JavaScript
  - > When programming in Processing, all additional classes defined will be treated as inner classes when the code is translated into pure Java before compiling.
Wikipedia - Arduino
- > The Arduino IDE supports the languages C and C++ using special rules of code structuring. The Arduino IDE supplies a software library from the Wiring project, which provides many common input and output procedures.
Stack Overflow - How to program an Arduino with C++
GitHub - ladislas/Bare-Arduino-Project
Arduino Forum - What is the difference between std::string and String
Stack Overflow -Strings in C++ class file for Arduino not compiling
Arduino Forum - Error #include <string> while compileing

Arduino,

I feedback.
Let me know what you think of this article on twitter @M3PGS or leave a comment below!