How do I use the conditional operator in Ruby

Question

How is the conditional operator       used in Ruby   For example  is this correct    lt   question   question size  gt  20   question question slice 0  20          question question   gt

User · Accepted Answer

It is the ternary operator  and it works like in C  the parenthesis are not required   It s an expression that works like   if this is a true value   then the result is this   else it is this   However  in Ruby  if is also an expression so  if a then b else c end     a   b   c  except for precedence issues  Both are expressions   Examples   puts  if 1 then 2 else 3 end      gt  2  puts 1   2   3                    gt  2  x   if 1 then 2 else 3 end puts x                            gt  2   Note that in the first case parenthesis are required  otherwise Ruby is confused because it thinks it is puts if 1 with some extra junk after it   but they are not required in the last case as said issue does not arise   You can use the  long-if  form for readability on multiple lines   question   if question size  gt  20 then   question slice 0  20          else    question end

User · Answer

Easiest way   param a   1 param b   2  result   param a     param b    Same      Not same     since param a is not equal to param b then the result s value will be Not same

User · Answer

Your use of ERB suggests that you are in Rails   If so  then consider truncate  a built-in helper which will do the job for you    lt   question   truncate question   length  gt 30    gt

User · Answer

A simple example where the operator checks if player s id is 1 and sets enemy id depending on the result  player id 1      player id  1  enemy id 2   enemy id 1     gt  enemy 2   And I found a post about to the topic which seems pretty helpful

User · Answer

puts true    true     false    gt   true    puts false    true     false    gt   false

User · Answer

The code condition   statement A   statement B is equivalent to   if condition    true   statement A else   statement B end

User · Answer

pst gave a great answer  but I d like to mention that in Ruby the ternary operator is written on one line to be syntactically correct  unlike Perl and C where we can write it on multiple lines    true    1   0   Normally Ruby will raise an error if you attempt to split it across multiple lines  but you can use the   line-continuation symbol at the end of a line and Ruby will be happy    true          1          0   This is a simple example  but it can be very useful when dealing with longer lines as it keeps the code nicely laid out   It s also possible to use the ternary without the line-continuation characters by putting the operators last on the line  but I don t like or recommend it    true      1     0   I think that leads to really hard to read code as the conditional test and or results get longer   I ve read comments saying not to use the ternary operator because it s confusing  but that is a bad reason to not use something  By the same logic we shouldn t use regular expressions  range operators       and the seemingly unknown  flip-flop  variation   They re powerful when used correctly  so we should learn to use them correctly        Why have you put brackets around true    Consider the OP s example    lt   question   question size  gt  20   question question slice 0  20          question question   gt    Wrapping the conditional test helps make it more readable because it visually separates the test    lt   question    question size  gt  20    question question slice 0  20          question question   gt    Of course  the whole example could be made a lot more readable by using some judicious additions of whitespace  This is untested but you ll get the idea    lt   question    question size  gt  20    question question slice 0  20                                                 question question    gt    Or  more written more idiomatically    lt   question   if  question size  gt  20                  question question slice 0  20                        else                  question question                end   gt    It d be easy to argument that readability suffers badly from question question too

[ruby] How do I use the conditional operator (? :) in Ruby?

Examples related to ruby

Examples related to ternary-operator

Examples related to conditional-operator