Ruby Number Classes and Conversions

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Just about everything in Ruby is an object. Perhaps one of most surprising things is that even numbers are objects in Ruby. Most other programming languages treat numbers as primitives (which essentially means they are the building blocks from which objects are built). This means that each number type is associated with a number class and can be manipulated using the methods of that class.




Ruby Number Classes

Ruby provides a number of built-in number classes. In this section we will explore some of the more commonly used classes.

Integer Class

The base class from which the following number classes are derived.


Fixnum Class

A Fixnum holds Integer values that can be represented in a native machine word (minus 1 bit). This effectively means that the maximum range of a Fixnum value depends on the architecture of the system on which the code is executing.

If an operation performed on a Fixnum exceeds the range defined by the system's machine word, the value is automatically converted by the interpreter to a Bignum.

Bignum Class

Bignum objects hold integers that fall outside the range of the Ruby Fixnum class. When a calculation involving Bignum objects returns a result that will fit in a Fixnum, the result is converted to Fixnum.

Float Class

The Float object represents real numbers based on the native architecture‘s double-precision floating point representation.

Rational Class

Rational implements a rational class for numbers.

A rational number is a number that can be expressed as a fraction p/q where p and q are integers and q is not equal to zero. A rational number p/q is said to have numerator p and denominator q. Numbers that are not rational are called irrational numbers.

Converting Numbers in Ruby

Numbers can be converted from one type to another using the Ruby Integer and Float methods. These methods take as an argument the value to be converted. For example:

Convert Floating Point Number to an Integer

Integer (10.898)
=> 10

Convert a String to an Integer

Integer ("10898")
=> 10898

Convert a Hexadecimal Number to an Integer

Integer (0xA4F5D)
=> 675677

Convert an Octal Number to an Integer

Integer (01231)
=> 665

Convert a Binary Number to an Integer

Integer (0b01110101)
=> 117

Convert an Character to the ASCII Character Code

For Ruby version 1.8 or earlier:

Integer (?e)
=> 101

For Ruby version 1.9 or later:

"e".getbyte(0)               #ASCII to Integer
=> 101

Similarly, we can perform conversions to floating point using the Float method:

Convert an Integer Floating Point

Float (10)
=> 10.0

Convert a String to Floating Point

Float ("10.09889")
=> 10.09889

Convert a Hexadecimal Number to Floating Point

Float (0xA4F5D)
=> 675677.0

Convert an Octal Number to a Floating Point

Float (01231)
=> 665.0

Convert a Binary Number to Floating Point

Float (0b01110101)
=> 117

Convert a Character to a Floating Point ASCII Character Code

For Ruby version 1.8 or earlier:

Float (?e)
=> 101.0

For Ruby version 1.9 or later:

"e".getbyte(0)
=> 101.0


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Ruby Variable ScopeRuby Methods