Ruby Merging variables in to a string

Question

I m looking for a better way to merge variables into a string  in Ruby   For example if the string is something like    The animal action the second animal   And I have variables for animal  action and second animal  what is the prefered way to put those variables in to the string

User · Answer

The standard ERB templating system may work for your scenario   def merge into string animal  second animal  action    template    The  lt   animal  gt   lt   action  gt  the  lt   second animal  gt     ERB new template  result binding  end  merge into string  tiger    deer    eats     gt   The tiger eats the deer   merge into string  bird    worm    finds     gt   The bird finds the worm

User · Answer

The idiomatic way is to write something like this    The   animal    action  the   second animal     Note the double quotes     surrounding the string  this is the trigger for Ruby to use its built-in placeholder substitution  You cannot replace them with single quotes     or the string will be kept as is

User · Answer

I would use the     constructor  as stated by the other answers  I also want to point out there is a real subtlety here to watch out for here   2 0 0p247  001  gt  first name    jim     gt   jim   2 0 0p247  002  gt  second name    bob     gt   bob   2 0 0p247  003  gt  full name      first name    second name      gt      first name     second name     not what we expected  expected  jim bob  2 0 0p247  004  gt  full name      first name    second name      gt   jim bob   correct  what we expected   While strings can be created with single quotes  as demonstrated by the first name and last name variables  the     constructor can only be used in strings with double quotes

User · Answer

The   animal  action   the   second animal  join        is another way to do it

User · Answer

You can use sprintf-like formatting to inject values into the string  For that the string must include placeholders  Put your arguments into an array and use on of these ways   For more info look at the documentation for Kernel  sprintf    fmt    The  s  s the  s  res   fmt    animal  action  other animal     using  -operator res   sprintf fmt  animal  action  other animal     call Kernel sprintf   You can even explicitly specify the argument number and shuffle them around    The  3 s  2 s the  1 s      cat    eats    mouse     Or specify the argument using hash keys    The   animal    action  the   second animal          animal   gt   cat    action  gt   eats    second animal   gt   mouse     Note that you must provide a value for all arguments to the   operator  For instance  you cannot avoid defining animal

User · Answer

This is called string interpolation  and you do it like this    The   animal    action  the   second animal     Important  it will only work when string is inside double quotes         Example of code that will not work as you expect    The   animal    action  the   second animal

User · Answer

You can use it with your local variables  like this   animal    Dog   action    licks   second animal    Bird    The    animal     action  the    second animal    the output would be   The Dog licks the Bird

[ruby] Ruby: Merging variables in to a string

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