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This is an implementation of a C++ standard library packaged as an Arduino library. The library supports teaching my CS-11M class by adding key C++ features into the Arduino environment.

The library is ported from uClibc++:

With a streams implementation from Andy Brown's Arduino Library:

Using printf() and scanf()

The ArduinoSTL header file contains code to bind a serial port of your choice to the stdio primitives. This happens automatically but the user must still call Serial.begin()

#include <ArduinoSTL.h>

void setup() {
  printf("Hello World\n");

Using cin an cout

When you include this header file you automatically get cin and cout based on Serial. See below for how to specify your own device. Here's an example sketch using cin and cout .

#include <ArduinoSTL.h>

using namespace std;

void setup() {
  cout << "Feed me an integers." << endl;

void loop() {
  int foo;
  if (cin >> foo) { 
    cout << "You fed me " << foo << endl;

Changing the Serial Port

You can change what serial port that cin, cout and printf() use. You can use built-in serial ports (e.g. Serial1 on Leonardo) or you can use software serial ports that implement Stream.

Using a Built-in Port

In src/ArduinoSTL.cpp change the value of ARDUINOSTL_DEFAULT_SERIAL. Leave the other defaults uncommented.

Using a SoftwareSerial port.

Set ARDUINO_DEFAULT_SERAL to NULL. Comment out the other defaults.

Here's an example sketch that uses SofwareSerial:

#include <ArduinoSTL.h>
#include <SoftwareSerial.h>

SoftwareSerial mySerial(0, 1);

namespace std { 
  ohserialstream cout(mySerial);
  ihserialstream cin(mySerial);

void setup() {

Avoiding Instantiation of cin and cout

Comment out ARDUINOSTL_DEFAULT_CIN_COUT and nothing will be instantiated. You must comment out this flag if you intend to select a non-default serial port. There's no appreciable overhead for using printf() so you cannot currently avoid initializaing it.

Known Issues

Printing of floats and doubles using cout ignores format specifiers.

uClibc seems to be fairly complete. Strings and vectors both work, even with the limited amount of heap available to Arduino. The uClibc++ status page can be found here:

Always use the latest Arduino IDE. This library uses the Arduino IDE Library Specification rev.2.1 with features only available on Arduino 1.6.10 and higher. The specification can be found here:


The uClibc++ library is licensed under the LGPL. This project adopts the LGPL to be compatible with the bulk of the code that it uses. Unless otherwise noted all code is licensed under the LGPL. There's one exception: