When you're in a loop there are occasions you want to say get me our of this loop NOW, or "I'm done with the current iteration. And those are the 'classic'
break and
continue statements from C, C++ and Java. Languages like Perl changed break to
last and continue to
next ... and added a
redo that asks for the current iteration to be rurun.
With me so far?
Now in Ruby ... you have
break, you have
next, you have
redo and you also have
retry ... which reenters the top of the loop. Wow - perhaps I had better provide an example?
for i in 1..5
print "How many do you need on day #{i}? "
nneed = gets.chomp.to_i
# next - don't order nothing; move on to next case
next if nneed == 0
# retry - whole thing to be redone on a 999 code
retry if [112,911,999].include?(nneed)
# redo - more than 10 ordered - must be a mistake
if nneed > 10 then print "Too many!\n"; redo; end
# break - code "-1" entered to exit on a short week
break if nneed == -1
print "We'll get #{nneed} on order for day #{i}\n"
end
By the way - if you've not seen much Ruby before, have a look through that example and taste a few of the constructs. It's really neat, and I expect I'll be writing a lot more about it in the future. ;-) . Source of this example
[here].
New technical articles on Ruby:
How classes are defined and used
Ruby's Control statements
String functions in Ruby
Ruby Regular Expressions
Modules, Mixins and Comparators (written 2006-12-03, updated 2011-01-29)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
R104 - Ruby - Control Structures [960] 1st, 2nd, 3rd revisited in Ruby - (2006-12-02)
[985] Equality in Ruby - == eql? and equal? - (2006-12-14)
[995] Ruby's case - no break - (2006-12-17)
[1163] A better alternative to cutting and pasting code - (2007-04-26)
[1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
[1582] Ruby, C, Java and more - getting out of loops - (2008-03-19)
[1587] Some Ruby programming examples from our course - (2008-03-21)
[1696] Saying NOT in Perl, PHP, Python, Lua ... - (2008-07-04)
[1738] Clean code, jump free (Example in Lua) - (2008-08-06)
[1870] What to do with a huge crop of apples - (2008-11-04)
[1887] Ruby Programming Course - Saturday and Sunday - (2008-11-16)
[1891] Ruby to access web services - (2008-11-16)
[1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
[2287] Learning to program in Ruby - examples of the programming basics - (2009-07-15)
[2471] A short form of if ... then ... else - (2009-10-23)
[2619] Passing code to procedures and yield in Ruby - (2010-02-02)
[2711] For loop - checked once, or evety time? Ruby v Perl comparison and contrast - (2010-04-07)
[2892] Alternative loops and conditionals in Ruby and Perl - (2010-07-28)
[2975] Why do I need brackets in Ruby ... or Perl, Python, C or Java - (2010-09-29)
[3156] Splitting data reading code from data processing code - Ruby - (2011-02-04)
[3158] Ruby training - some fresh examples for string handling applications - (2011-02-05)
[3159] Returning multiple values from a function call in various languages - a comparison - (2011-02-06)
[3200] How a for loop works Java, Perl and other languages - (2011-03-12)
[3253] Is this number between? Does this list include? - Ruby - (2011-04-18)
[3254] Multiple inputs, multiple out, ruby functions - (2011-04-19)
[3397] Does a for loop evaluate its end condition once, or on every iteration? - (2011-08-18)
[3422] Assigning values to variables within other statements - Ruby - (2011-09-07)
[3619] Ruby v Perl - a comparison example - (2012-02-21)
[3620] Finding the total, average, minimum and maximum in a program - (2012-02-22)
[3769] Muttable v immutable and implications - Ruby - (2012-06-20)
[4322] Learning to Program - the conditional statement (if) - (2014-11-21)
[4323] Learning to program - Loop statements such as while - (2014-11-22)
[4370] Conditionals, loops and methods in Ruby - a primer with simple examples - (2014-12-29)
[4402] Finding sum, minimum, maximum and average in Python (and Ruby) - (2015-01-19)
[4503] Separating your code for easier testing, understanding and re-use; example in Ruby - (2015-06-02)
[4504] Where does Ruby load modules from, and how to load from current directory - (2015-06-03)
[4674] Alternating valuses / flip-flop / toggle - example in Ruby - (2016-05-17)
P206 - Perl - More Loops and Conditionals [138] Perl - redo and last without a loop - (2004-12-02)
[299] What - no switch or case statement? - (2005-05-03)
[657] The ternary operator in Python - (2006-03-25)
[1191] Smart English Output - via PHP and Perl ? : operator - (2007-05-18)
[1825] Question Mark - Colon operator (Perl and PHP) - (2008-10-08)
[2815] switch and case, or given and when in Perl - (2010-06-17)
[2817] Setting a safety net or fallback value in Perl - (2010-06-19)
[2824] A pint of Black Rat, and a lazy barman - (2010-06-25)
[2832] Are you learning Perl? Some more examples for you! - (2010-06-27)
[2967] Multiway branches in Perl - the given and when syntax - (2010-09-22)
[2972] Some more advanced Perl examples from a recent course - (2010-09-27)
[3398] Perl - making best use of the flexibility, but also using good coding standards - (2011-08-19)
[3914] While, for, foreach or something else to loop. - (2012-11-06)
H104 - PHP - Control Statements [340] Code and code maintainance efficiency - (2005-06-08)
[353] Wimbledon Neck - (2005-06-20)
[406] Assignment, equality and identity in PHP - (2005-08-08)
[421] Don't repeat code - use loops or functions - (2005-08-21)
[863] Double and Triple equals operator in PHP - (2006-09-12)
[1199] Testing for one of a list of values. - (2007-05-22)
[1477] Decisions - small ones, or big ones? - (2007-12-18)
[2304] Extracting real data from an exported file in PHP or Perl - (2009-07-25)
[2912] Predictions for the seagull population - (2010-08-09)
[3895] Flowchart to program - learning to program with Well House - (2012-10-14)
C203 - C and C based languages - Conditionals and Loops [2002] New C Examples - pointers, realloc, structs and more - (2009-01-20)
[2570] Function Prototypes in C - (2010-01-11)
[3004] Increment operators for counting - Perl, PHP, C and others - (2010-10-18)
[3121] New year, new C Course - (2011-01-05)
[3243] Breaking the running sequence - an introduction to conditional statements and loops - (2011-04-11)
[3384] Loops - a comparison of goto, while and for - (2011-08-10)
[4337] Learning to program sample program - past its prime, but still useful - (2014-12-02)
Some other Articles
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