Sometimes, you might accidentally try to combine text with a number. Ruby won't understand what to do in that case:
irb(main)> "Apollo 11 landed on the moon in " + 1969
TypeError: no implicit conversion of Integer into String
from (irb):in `+'
Don't panic when you see error messages like this. This TypeError simply means
that we tried to add two objects together of different types:
one object was text but the other was a number. The + operator isn't
smart enough what to do in this case.
There are two ways to solve this problem. The first uses a type conversion, and the second uses string interpolation.
We can tell Ruby to convert the number 1969 into its textual representation,
like this: 1969.to_s. The .to_s part converts the number
into a "string" of text. We will talk more about strings in the chapter
on Classifications.
irb(main)> "Apollo 11 landed on the moon in " + 1969.to_s
=> "Apollo 11 landed on the moon in 1969"
Another solution is to use string interpolation, which enables you to embed any Ruby expression right inside of a piece of text:
irb(main)> "Apollo 11 landed on the moon in #{1969}"
=> "Apollo 11 landed on the moon in 1969"
See that strange #{ } part? That's the special signal that
we want Ruby to first evaluate the expression inside. Here's
another example:
irb(main)> "There are #{4 + 3 + 2 + 1} bowling pins."
=> "There are 10 bowling pins."
We can create a text object that represents several lines of text.
We can use a special character sequence, \n, to represent a new line:
irb(main)> "Roses are red\nViolets are blue\nRuby is cool\nAnd so are you\n"
=> "Roses are red\nViolets are blue\nRuby is cool\nAnd so are you\n"
Hmmm, that didn't seem to do anything special yet, but they will take effect
when we use the print function:
irb(main)> print("Roses are red\nViolets are blue\nRuby is cool\nAnd so are you\n")
Roses are red
Violets are blue
Ruby is cool
And so are you
=> nil
print() not print ().