We can use scalar variables in strings
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$h= "World"; $hw= "Hello $h"; # sets $hw to "Hello World"
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$h= "World"; $hw= "\UHello $h"; # sets $hw to "HELLO WORLD"
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showing how \U and similarly \L operate on interpolated variables
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As mentioned, there is NO interpolation for single quoted strings
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There is also no recursion as illustrated below:
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$fred= "You over there"; $x= '$fred'; $y= "Hey $x"; # sets $y as "Hey $fred" with no interpolation
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Use \$ to ensure no interpolation where you need real $ character
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$fred= "You over there"; $y= "Hey \$fred"; # sets $y as "Hey $fred" with no interpolation whereas:
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$fred= "You over there"; $y= "Hey $fred"; # sets $y as "Hey You over there" with interpolation used
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Use ${var} to remove ambiguity as in
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$y= "Hey ${fred}followed by more characters";
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