Invalid argument supplied for foreach()

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It often happens to me to handle data that can be either an array or a null variable and to feed some foreach with these data.

$values = get_values();

foreach ($values as $value){
  ...
}

When you feed a foreach with data that are not an array, you get a warning:

Warning: Invalid argument supplied for foreach() in […]

Assuming it’s not possible to refactor the get_values() function to always return an array (backward compatibility, not available source code, whatever other reason), I’m wondering which is the cleanest and most efficient way to avoid these warnings:

  • Casting $values to array
  • Initializing $values to array
  • Wrapping the foreach with an if
  • Other (please suggest)

20 Answers
20

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