Logic and Conditionals
Classes, variables, and simple methods may carry some basic applications a surprisingly long way, but most applications need more logic. This quick tour through Rubyâs control structures will give you more tools for building your applications.
Your program logic will depend on combining variables with operators into expressions. Those expressions then get resolved into results, which may be used to assign values to variables, or to give an answer about whether a test passed or failed. Most Ruby operators should look familiar if youâve ever used a programming language before. The following table shows an abbreviated list of operators youâre likely to encounter in your first forays into Rails.
Addition, concatenation, making numbers positive
Subtraction, removing from collections, making numbers negative
Modulo (remainder from integer division)
Exponentiation (2**3 is 8, 10**4 is 1000)
Shift bits left, or add to a collection
Less than or equal to
Greater than or equal to
General comparisonâless then yields â1, equal
returns 0, greater than 1, and not comparable
Equal to (note that a single
Tests to see whether objects are of same class
Not equal to
Tests a regular expression pattern for a match (see AppendixÂ C)
Tests a regular expression pattern for no match
Boolean AND (use to combine test expressions)
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