We can make our programs much more interesting if we allow the users of the program to interact with them by supplying input. We can do this with the gets method (pronounced “get S”, short for “get string”), which will pause the program and wait for the user to type something in the terminal and press return. The return value of the gets method will be a String containing what the user typed, which we can store in a variable and then process further like any other String.
For example, rather than saying “Hello, world!”, let’s have the computer say hello to the user by name instead. When you run this program, it will pause after saying "What's your name?" and you will have to type something in and press return. Click on the terminal to put focus there, and then you’ll be able to type into it:
Great! Our first user input. However, you’ll notice a couple of things. First of all, there’s a \n sneaking into the input. \n represents a newline character, and it’s in there because of the return that is pressed to submit the input.
If you want to see the newline in action, we can use a different printing method called puts (pronounced “put S”, short for “put string”). puts is actually the printing method that is used most when crafting the final output of command-line programs; as opposed to p, which is used most for making the invisible visible while debugging. Try switching
p "Hello, " + their_name + "!"
to
puts "Hello, " + their_name + "!"
and see how the output is different.
You can see that the quotes around the string are removed, which makes sense if you’re actually displaying output to a user and not debugging — users should not know or care about the quotes around Ruby string literals. And the newline character causes a line break when a string is printed with puts, as it should.
Most of the time, we’ll stick with p, since it provides more details while debugging; but it’s good to know that puts exists.
We almost never want to keep the \n that results from the return keypress that submits the user’s input. Fortunately, the handy .chomp method does exactly what we need — if there’s a \n at the end of a string, it will remove it; if there isn’t, it does nothing. So, in practice, when we call gets we almost always tack a .chomp on to it immediately. Try modifying the program to:
their_name = gets.chomp
and see how it’s different.
Test your skills: