Dart Runes and Graphemes

Runes and Graphemes data types in Dart

Runes and Graphemes

Runes are the special string of Unicode UTF-32 bits that represent the special syntax. Unicode defines a unique numeric value for each letter, digit, and symbol.

The Dart Runes are provided by the ‘ dart : core ’ library or ‘ package : characters ’.

Syntax of representing runes is :

\uXXXX, where XXXX is a 4-digit hexadecimal value

For example,

\u2665 corresponds to a heart character.

Program

import 'package:characters/characters.dart' ;


void main( )
{
  print( ' \u2665 ' ) ;
  print( ' \u{ 1f606 } ' ) ;
}

Output:

The String code runes can be accessed using the following three methods :

• Using String.codeUnitAt( ) function
• Using String.codeUnits property
• Using String.runes property

String.codeUnitAt( ) Function

This function returns the 16 – bit UTF – 16 code unit corresponding to the string at a particular index passed to the function as an argument.

Implementation = String.codeUnitAt( int index ) ;

Program

void main( ) 
{  
  // initializing string str
  String str = ' Let us understand codeUnits Property ' ;  
  
  // using codeUnitAt function to return the code unit at index 0
  print( str.codeUnitAt( 0 ) ) ;  
  
  // using codeUnitAt function to return the code unit at index 2
  print( str.codeUnitAt( 2 ) ) ;  
} 

Output :

32
101

String.codeUnits Property

This property returns the list of the UTF – 16 code units of the specified string.

Implementation = String. codeUnits ;

Program

void main( )
{ 
   // initializing string str
   String str = ' This tutorial teaches Runes ' ; 
  
   print( ' \n The code units are as follows : \n ' );
  
   // Using codeUnits property to print the code units of each string
   print( str.codeUnits ) ; 
}

Output :

The code units are as follows : 
 [32, 84, 104, 105, 115, 32, 116, 117, 116, 111, 114, 105, 97, 108, 32, 116, 101, 97, 99, 104, 101, 115, 32, 82, 117, 110, 101, 115, 32]

String.runes Property

This property returns an iterable of Unicode code – points of the passed string.Runes.

Implementation = String.runes

Program

void main( )
{ 
   " This teaches Runes ".runes.forEach( ( int rune ){ 
      var character = new String.fromCharCode( rune ) ; 
      print( character ) ; 
   } ) ;  
}

Output:

T
h
i
s
 
t
e
a
c
h
e
s
 
R
u
n
e
s