Scalar Variables and Operators

String Interpolation (Variable Substitution)

• When a string literal is double quoted, it is subject to variable interpolation .
• The terms Variable Interpolation are simply big words programmers use to impress each other. If they said variable expansion or variable substitution it would not sound nearly impressive enough.
• Example:

  $MyName = "Reepicheep";
  $Greeting = "Hello $MyName\n";  # Greeting is now "Hello Reepicheep\n"
  

• This is only done once. If the result of the substitution contains a $ character, no further substitutions are performed.
• If you don't wish the substitution to be performed, use the \$ in place of your $ characters. Alternately you could concatenate single quoted strings to do the same thing, as single quoted strings are not variable interpolated.
• Perl decides what constitutes a variable by being greedy... it tries to find the longest possible variable match. You can use the curly braces to explicitly tell Perl which variable is the one you want.

• Example:

  $Greeting = "Hello";
  $GreetingFormal = "Good Day";
  # Make string "Good Day Reepicheep\n"
  $GreetingStringOne = "$GreetingFormal Reepicheep\n";
  # Make string "HelloFormal Reepicheep\n"
  $GreetingStringTwo = "${Greeting}Formal Reepicheep\n";
  

• You could use concatenation to remove any ambiguity in variable names as well.

• Example:

  $Greeting = "Hello";
  $GreetingFormal = "Good Day";
  # Make string "Good Day Reepicheep\n"
  $GreetingStringOne = "$GreetingFormal Reepicheep\n";
  # Make string "HelloFormal Reepicheep\n"
  $GreetingStringTwo = "$Greeting" . "Formal Reepicheep\n";