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 :

Properties	Description
hashcode	Returns the hash code for a numerical value. It returns the same value for int and double when the value provided is the same. Implementation = int get hashchode;
isFinite	Checks the finiteness of the number and accordingly returns true or false. All integers are finite. The non-finite numbers are NaN values, positive infinity, and negative infinity only. Implementation = bool get isFinite;
isInfinite	Checks the infiniteness : positive or negative, of the number and returns true or false accordingly. Implementation = bool get isInfinite;
isNan	Checks whether the number is NaN ( Not-a-Number value ) and returns true or false accordingly. Implementation = bool get isNan;
isNegative	Checks whether the number is negative or not and returns true or false accordingly. Implementation = bool get isNegative;
sign	Assesses the sign of the number and returns -1, 0, or 1 accordingly. -1 = number is less than zero; negative  1 = number is greater than zero; positive  0 = number is equal to zero Implementation = num get sign;
iseven	Checks whether a number is even and returns true or false accordingly. Implementation = bool get isEven;
isOdd	Checks whether a number is odd and returns true or false accordingly. Implementation = bool get isOdd;

Methods

Methods	Description
abs( )	Returns the absolute value of the given number, which is the number itself. Implementation = num abs( );
ceil( )	Returns the least integer not smaller than the given number. It basically rounds the number to the positive infinity. Implementation = int ceil( );
clamp( num lowerLimit, num upperLimit )	Returns the given number clamped in the range lowerLimit – upperLimit. Implementation = clamp( num lowerLimit, num upperLimit );
compareTo( num other )	Compares the given number with other and returns a negative number if the given number is less than the other, a positive value if the given number is greater than the other, and zero if they are equal. Implementation = int compareTo( num other );
floor( )	Returns the greatest integer not greater than the given number. It basically rounds the number to the negative infinity. Implementation = int floor( );
remainder( num other )	Returns the remainder of the division of a given number by other. Implementation = num remainder( num other );
round( )	Returns the integer value closest to the given number. The number must be finite in order to use this method. Implementation = int round( );
toDouble( )	Converts a given number into double and returns the value of double type. In case an integer value can not be represented as double accurately, an approximation is returned. Implementation = double toDouble( );
toInt( )	Converts a given number into int and returns the value of int type. Implementation = int toInt( );
toString( )	Converts a given number into an equivalent shortest string and returns the same. Implmentation = String toString( );
truncate( )	Returns the integer after discarding or truncating the fractional part of the given number. It rounds fractional values to zero. Implementation = int truncate( );