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Ruby Conversions

A conversion changes a value from one type into another type. Ruby conversion methods have short names like to_i and to_s.

A string becomes a number

to_i changes a string of digits into an integer. The new number can join in maths at once.

puts "42".to_i + 8

A float fixes a division

Integer division drops the fraction part. Changing 7 into a float with to_f keeps the fraction part.

puts 7 / 2
puts 7.to_f / 2

A number becomes a string

to_s changes a number into a string. Printing the class of the new value proves its type.

puts 42.to_s.class

Same digits, two types

One string of digits can become an integer or a float. The float form prints with a decimal point.

puts "12".to_i
puts "12".to_f

Example

puts "42".to_i + 8
puts 7.to_f / 2
puts 100.to_s.class

Key points

  • Use to_i to change a value into an integer.
  • Use to_f to change a value into a float.
  • Use to_s to change a value into a string.
  • A string of digits can become a number with to_i.
  • Changing one value in a division to a float keeps the fraction part.

In this example, the first line turns the digits 42 into a number and adds 8, printing 50. The second line changes 7 into a float and divides by 2, printing 3.5. The third line changes 100 into a string and prints its class, String.

Note

In these names, i stands for integer, f stands for float and s stands for string.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Programiz Ruby Compiler

Exercise

What does puts "6".to_i * 3 print?