This course will be retired on November 27, 2017. We recommend "Ruby Basics" for uptodate content.
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Ruby follows the same conventions as math! That means that operators have precedence over other operators and follow the order of operations.
Ruby Operator Precedence
( ) # Parentheses
! # Not
** # Exponentiation
% / * # Modulus, Division, Multiplication
+  # Addition and Subtraction

0:00
When we have multiple operators on the same line of code,

0:03
the order in which things are evaluated can change

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depending on how important the operators are to Ruby.

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This is just like regular math where parentheses are evaluated first,

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then exponents, multiplication and division, then addition and subtraction.

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We group statements the same way in Ruby using parentheses.

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After that, the different operators have different levels of precedents.

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This gives us a lot of power when writing Ruby programs.

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Let's see how that works now using Workspaces.

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Okay. So I have just launched a new

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Ruby workspace.

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And, we're gonna do our work in IRB here.

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So I'm gonna drag that up, and in the consult area type irb, and press Enter.

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Now let's go ahead and just see how some of these operators work.

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When we type them all out on the same line,

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let's see how Ruby interprets what's happening.

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So if I were to do 1 plus 1, it would be 2, but

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if I do 1 plus 1 and then I do times 2, it's 3.

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Now if it were just going left to right, we would expect that to be 2 times 2.

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But, actually, Ruby is interpreting 1 times 2 first,

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and then adding 1 to that, so that becomes 3.

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Now, if instead of [SOUND] multiplication,

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[SOUND] we did subtraction, that all works the same way.

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So lets see, 1 plus 1 minus 5, [SOUND] that becomes negative 3.

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So that would be 2 minus 5.

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You know if we wanted to we could change this.

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So let's say we had 10 and

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we wanted to subtract [SOUND] 10 and 1,

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we could just surround it with parentheses and

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that would make this part more important.

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And you can do that any number of times,

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so if we said 2 times 2, times 4.

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[SOUND] Looks like Workspaces got a little funny there.

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Let's try that again.

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2 times 2, times 4 is 16.

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[SOUND] And we can do that, minus 6.

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[SOUND] Now multiplication and division, and modulus have the same precedence.

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After that is addition and subtraction.

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[SOUND] And clear my screen here, and

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we'll do 10 modulus 5 is 0,

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[SOUND] plus 1 [SOUND] is 1.

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So we can see that the modulus here has more precedence than the plus.
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