String class

String()

String

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 variable, showing a specific number of decimal places

// SYNTAX
String(val)
String(val, base)

// EXAMPLES
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(34.5432, 2);                // using a float showing only 2 decimal places shows 34.54

// PROTOTYPES
String(const char *cstr = "");
String(const char *cstr, unsigned int length);
String(const String &str);
explicit String(char c);
explicit String(unsigned char, unsigned char base=10);
explicit String(int, unsigned char base=10);
explicit String(unsigned int, unsigned char base=10);
explicit String(long, unsigned char base=10);
explicit String(unsigned long, unsigned char base=10);
explicit String(float, int decimalPlaces=6);
explicit String(double, int decimalPlaces=6);

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) gives you the String "13". You can use other bases, however. For example, String thisString = String(13, HEX) 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) gives you the String "1101", which is the binary representation of 13.

Parameters:

• val: a variable to format as a String - string, char, byte, int, long, unsigned int, unsigned long
• base (optional) - the base in which to format an integral value

Returns: an instance of the String class