String Constructors

This example will go over how to use string constructors.

Relevant Groundwork

The String object allows you to manipulate strings of text in a variety of useful ways. You can append characters to Strings, combine Strings through concatenation, get the length of a String, search and replace substrings, and more. This tutorial shows you how to initialize String objects.

 String stringOne = "Hello String";                   // using a constant String
 String stringOne =  String('a');                     // converting a constant char into a String
 String stringTwo =  String("This is a string");      // converting a constant string into a String object
 String stringOne =  String(stringTwo + " with more");// concatenating two strings
 String stringOne =  String(13);                      // using a constant integer
 String stringOne =  String(analogRead(0), DEC);      // using an int and a base
 String stringOne =  String(45, HEX);                 // using an int and a base (hexadecimal)
 String stringOne =  String(255, BIN);                // using an int and a base (binary)
 String stringOne =  String(millis(), DEC);           // using a long and a base

All of these methods are valid ways to declare a String object. They all result in an object containing a string of characters that can be manipulated using any of the String methods. To see them in action, upload the code below onto an Arduino and open the Serial Monitor. You’ll see the results of each declaration. Compare what’s printed by each println() to the declaration above it.

Hardware Required

MSP-EXP430G2 LaunchPad

Circuit

Only LaunchPad is required for this example.

Image developed using Fritzing. For more circuit examples, see the Fritzing project page.

Schematic

Code Explanation

In the program, we use string contructors to create strings from other data types.

Code

/*
   String constructors

 Examples of how  to create strings from other data types

 created 27 July 2010
 modified 30 Aug 2011
 by Tom Igoe

 This example code is in the public domain.
 */

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);

  // send an intro:
  Serial.println("\n\nString Constructors:");
  Serial.println();
}

void loop() {
  // using a constant String:
  String stringOne = "Hello String";
  Serial.println(stringOne);      // prints "Hello String"

  // converting a constant char into a String:
  stringOne =  String('a');
  Serial.println(stringOne);       // prints "a"

  // converting a constant string into a String object:
  String stringTwo =  String("This is a string");
  Serial.println(stringTwo);      // prints "This is a string"

  // concatenating two strings:
  stringOne =  String(stringTwo + " with more");
  // prints "This is a string with more":
  Serial.println(stringOne);

  // using a constant integer:
  stringOne =  String(13);
  Serial.println(stringOne);      // prints "13"

  // using an int and a base:
  stringOne =  String(analogRead(A0), DEC);
  // prints "453" or whatever the value of analogRead(A0) is
  Serial.println(stringOne);

  // using an int and a base (hexadecimal):
  stringOne =  String(45, HEX);
  // prints "2d", which is the hexadecimal version of decimal 45:
  Serial.println(stringOne);

  // using an int and a base (binary)
  stringOne =  String(255, BIN);
  // prints "11111111" which is the binary value of 255
  Serial.println(stringOne);

  // using a long and a base:
  stringOne =  String(millis(), DEC);
  // prints "123456" or whatever the value of millis() is:
  Serial.println(stringOne);

  // do nothing while true:
  while(true);

}

Working Video

Try it out

Use all the possible string constructors in a sketch.