String functions

Updated on 2 December 2021

dev board Arduino UNO

firmware Arduino

chip ATmega328P

This tutorial is more than 1 year old. If the steps below do not work, then please check the latest versions and the documentations of the individual tools used.

Buy the components

Arduino UNO R3

Code

Download code string-functions.ino

String sample;
String animal = "lion";

void setup() {
  Serial.begin(9600);
  Serial.println("String functions...");

  Serial.print("string.length(): ");
  Serial.println(animal.length());
}

void loop() {
  temperature(sample);

  Serial.print("Temperature returned: ");
  Serial.println(sample);

  delay(1000);
}

void temperature(String &value) {
  value = String(random(0, 30));
}

Makefile

BOARD?=arduino:avr:uno
PORT?=/dev/cu.usbmodem14*
BUILD=build

.PHONY: default lint all flash clean

default: lint all flash clean

lint:
	cpplint --extensions=ino --filter=-legal/copyright,-runtime/references *.ino

all:
	arduino-cli compile --fqbn $(BOARD) --output-dir $(BUILD) ./

flash:
	arduino-cli upload --fqbn $(BOARD) --port $(PORT) --input-dir $(BUILD)

clean:
	rm -r build

Prototype

A photo of the actual setup.

Serial console

Serial output from the firmware.

Description

Examples of various String functions and how to pass the function a reference to a String object that you want to write to.

References

String Arduino