Numbers

Programs use numbers everywhere. Many numeric types and conversions can be done in Ruby. Many programs use the Integer and Float built-in methods.

Ruby examples

Methods like Float() and Integer() can perform simple conversions. Strings can be converted to numbers, and back again as well.

Integer, Float

Here we convert string data to number types. A string may contain digits but not be a number. With the Integer conversion, we convert it to one. We also use Float.

Here We convert the string "1234" into an Integer. And we convert a string with floating-point data into a Float.

Then We add the 2 numbers together. This shows they are no longer strings, which could not be added in this way.

# Two strings with numeric contents.
value1 = "1234"
value2 = "1234.5678"

# Convert strings to numbers.
number1 = Integer(value1)
number2 = Float(value2)

# Print numbers.
print "Number1: ", number1, "\n"
print "Number2: ", number2, "\n"

# Add numbers together.
# ... Could not be done with strings.
number3 = number1 + number2

# Print final number.
print "Number3: ", number3, "\n"Number1: 1234
Number2: 1234.5678
Number3: 2468.5678

Exponents

We can directly use exponents, with the two-star operator. In this program, we raise a value to the power of two, and then to the power of three.

Tip More advanced mathematical operations are available as methods in the Math class.

# An initial value.
value = 3

# Square the value.
square = value ** 2

# Cube the value.
cube = value ** 3

# Display our results.
puts square
puts cube9
27

Zero, nonzero

Zero() returns true or false. If the number is zero, it returns true. Otherwise, it returns false. Nonzero meanwhile returns the original number if it is not zero.

And If the number is zero, nonzero returns nil. So it returns the number with 0 changed to nil.

value = 0

if value.zero?
    puts "A"
end

if value.nonzero?
    puts "B" # Not reached.
end

value = 1

if value.nonzero?
    puts "C"
endA
C

Eql operator

Unlike the "==" operator, eql compares types. So a floating point number, like 1.0, is not equal to an Integer number like 1. The == operator treats them as equal.

Tip Using the == operator is superior in most programs. The eql method just adds complexity—1.0 usually should equal 1.

value1 = 1
value2 = 1.0
value3 = 1

if value1.eql? value2
    puts "A" # Not reached.
end

if value1 == value2
    puts "B"
end

if value1.eql? value3
    puts "C"
endB
C

`Random` numbers

With the rand method we generate a pseudo-random number. The srand method is used to seed our random number generator.

Math

Some numeric operations can be done directly, with operators like + or minus. But many math methods exist, included for easy access. These handle more complex things like sqrt.

A summary

Tasks that involve numbers are often language-specific. In Ruby, we have many helpful operators available on numbers. We convert and manipulate numbers with ease.