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Variables can hold numbers, text, a calendar date, or any other piece of data that can be stored in your computer's memory.
- Variables in a programming language are like variables in algrebra, but they can hold other things besides numbers. They can hold text, or a calendar date, or any other piece of data that can be stored in your computer's memory.
- When you assign a value to a variable, you're giving that value a name that you can refer to it by.
- You assign a value to a variable with a single equals sign:
=
number = 4
greeting = "hello"
- We can then use that variable anywhere we might use the original piece of data.
puts number # 4
puts greeting # "hello"
puts number + 2 # 6
puts 12 - number # 8
- If we change the value the variable holds, the remainder of the program will use that new value instead of the old one.
number = 6
greeting = "hi"
puts number # 6
puts greeting # "hi"
puts number + 2 # 8
puts 12 - number # 6
- We can even replace the value a variable holds in the middle of a program.
- Valid variable names - same as method names.
- All lower case
- Numbers are legal but rarely used
- Snake case - separate words with underscores.
word = "hi"
multiple_words = "hi there"
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