Chapter 4
Variables and Assignment

So far, whenever we have putsed a string or a number, the thing we putsed is gone. What I mean is, if we wanted to print something out twice, we would have to type it in twice:

It would be nice if we could just type it in once and then hang on to it…store it somewhere. Well, we can, of course. It would have been insensitive to bring it up otherwise.

To store the string in your computer’s memory for use later in your program, you need to give the string a name. Programmers often refer to this process as assignment, and they call the names variables. A variable name can usually be just about any sequence of letters and numbers, but in Ruby the first character of this name needs to be a lowercase letter. Let’s try that last program again, but this time I will give the string the name my_string (though I could just as well have named it str or myOwnLittleString or henry_the_8th):

Whenever you tried to do something to my_string, the program did it to '...you can say that again...' instead. You can think of the variable my_string as “pointing to” the string '...you can say that again...'. Here’s a slightly more motivated example:

Also, just as we can assign an object to a variable, we can reassign a different object to that variable. (This is why we call them variables—what they point to can vary.)

Of course, variables can point to any kind of object, not just strings:

In fact, variables can point to just about anything…except other variables. So, what happens if we try the following?

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Figure 1. Variables point to values

On the second line, when we tried to point var2 to var1, it really pointed to 8 instead (just like var1 was pointing to). Then on the eighth line, we had var1 point to the string 'eight', but since var2 was never really pointing at var1, it stays pointing at the number 8. If you like to think about these things visually, it might help to look at the figure Figure 1, ​Variables point to values​.