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String

String()

Description

Constructs an instance of the String class. There are multiple versions that construct Strings from different data types (i.e. format them as sequences of characters), including:

  • a constant string of characters, in double quotes (i.e. a char array)
  • a single constant character, in single quotes
  • another instance of the String object
  • a constant integer or long integer
  • a constant integer or long integer, using a specified base
  • an integer or long integer variable
  • an integer or long integer variable, using a specified base
  • a float or double, using a specified decimal palces

Constructing a String from a number results in a string that contains the ASCII representation of that number. The default is base ten, so

String thisString = String(13);
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gives you the String "13". You can use other bases, however. For example,

String thisString = String(13, HEX);
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gives you the String "D", which is the hexadecimal representation of the decimal value 13. Or if you prefer binary,

String thisString = String(13, BIN);
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gives you the String "1101", which is the binary representation of 13.

Syntax

String(val)
String(val, base)
String(val, decimalPlaces)

Parameters

val: a variable to format as a String - string, char, byte, int, long, unsigned int, unsigned long, float, double
base (optional) - the base in which to format an integral value
decimalPlaces (only if val is float or double) - the desired decimal places

Returns

an instance of the String class

Examples

All of the following are valid declarations for Strings.

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
String stringOne =  String(5.698, 3);                                // using a float and the decimal places
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See also

Reference Home

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The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.

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