Ruby - Control Structures

Ruby module R104

Control Structures

Exercises, examples and other material relating to training module R104. This topic is presented on public courses Learning to program in Ruby, Ruby Programming

Background

Conditional statements, loops, and functions you would expect. Exceptions, iterators and methods may be new to you. And you'll need to know how to write conditions too.

Related technical and longer articles

Converting to Ruby? Start here
Conditionals, loops, and iterators in Ruby

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3620	Finding the total, average, minimum and maximum in a program There are a number of programming techniques which the experienced coder takes for granted, but which aren't necessarily intuitive for the newcomer. Call them "design techniques" or "design patterns" that need to be learned, if you want some fashionable buzzwords. • To produce the sum of a stream ...	2012-10-08
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3397	Does a for loop evaluate its end condition once, or on every iteration? All the languages that we teach have a for loop or the equivalent, which is a clean way of repeating a block of code with a rising or falling index number. It's used in many circumstances - for example in iterating through the months of the year (for m goes from 1 to 12) of in stepping through all ...	2012-04-15
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1582	Ruby, C, Java and more - getting out of loops break and continue statements have been available for loop control for many years, and others functionallity has been added such as Perl's redo. From today's Ruby Course, here's a table that compares these loop controls in Ruby to similar commands in the other languages that I have been discussing ...	2008-03-19
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2926

Examples from our training material

amp_pass	Passing code blocks to procedures
collect	for and each loops over an array. Also sorting
condi.rb	Example of Ruby conditionals
ctors.rb	Comparators - what is true?
cx	between and include
d2.6	if elsif elsif else
d2.7	while, until and for loops - comparison
dbu	Variable and method of same name
ddd.rb	Iterators in Ruby
dice	Throwing dice, summing, printing average
dm.rb	Defining and using a method
dm2.rb	Method, parameter, optional parameter
dm3.rb	Dynamic redefinition of a method
doubleret	multiple returns and unlimited parameters
ex	Class exercise - ordering lunches
exx	Putting common code in a name block (function)
five	Some unusual conditionals and loops
howcome	Multiple actions in a single statement
ident	mutable object (array)
lazyops.rb	Lazy operators
llen	Methods and default parameter
llen2	calculating default parameters
llen3	Default a parameter to nil
loop.rb	Loop in ruby - run until it breaks
loopy.rb	Loop structures in Ruby
mi	redefine a method in Ruby
mwpar	In Ruby you can redefine a function ...
rmi	Multiple return values from a function
rubber	? : conditional operator in Ruby
scram.rb	Break redo next and retry
sid	Loop and conditional - exercise
u1	How many teams needed?
vcx	Quick first validation example
yetan	immutable object (integer)
yrb	yield (co-routines / generator)

Background information

Some modules are available for download as a sample of our material or under an Open Training Notes License for free download from http://www.training-notes.co.uk.

Topics covered in this module

Blocks and the if statement.
Writing conditions.
Comparative, boolean and range operators.
Conditionals - if, unless, case, etc.
Loops - while, for in, until, etc.
break, next, retry and redo.
defined? and ternary operators.

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