Dart Numbers

Dart provides an in-built data type ‘Numbers’ that provides two types of values:

1. int
2. double

1. int data type

int data type supports integer values, and their size or values range is platform-dependent. Integers are numbers without a decimal point. On the native platforms, values range from -2⁶³  to 2⁶³ – 1. On the web platforms, integer values correspond to JavaScript numbers that range from -2⁵³ to 2⁵³ – 1.

Example,

int time = 2; 
int x = 5e2;

2. double data type

double data type supports 64-bit floating-point numbers, basically decimal values.

Example,

double rate = 8.5;
double pi = 3.14;
double x = 1;

In the last example, the compiler performs implicit type-casting, converting integer value into decimal whenever required.

Instead of using keywords ‘int’ and ‘double’ separately for integer and decimal values, respectively, we can simply use the ‘num’ keyword.

Variable declared with num keyword can have both integer and decimal values.

num area = 9;
num area = 9.9;

The num data type provides basic operators like +, -, /, and * and the int data type specifies bitwise operators like bitwise left shift and right shift (<< , >>), AND (&), OR (|), and XOR (^).

Example:

Consider the following code in Dart to understand the above points more clearly,

import ‘dart:io’;
void main( )
{
  // no type annotation. Compiler automatically infers integer value
  var a = 5 ;


  // Compiler automatically infers double value
  var b = 5.5 ;
  
  // declaring c as integer type
  int c = 6 ;
  
  // declaring variables as double type
  double d = 6.2 ;
  double e = 5 ; // compiler implicitly converts integer into double value when required
  
  /* with num compiler automatically interprets integer or double type by
  analyzing the value assigned */
  num f = 9 ;
  
  num g = 9.9 ;
  
  print( ' \n Value of a : $a \n Value of b : $b \n Value of c : $c \n Value of d : $d \n Value of e : $e \n Value of f : $f \n Value of g : $g ' );
}

Output :

Value of a : 5   
Value of b : 5.5 
Value of c : 6   
Value of d : 6.2 
Value of e : 5.0 
Value of f : 9   
Value of g : 9.9

Constructors :

• num(  )

Properties of num class :

Methods