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cast_for_arithmetic

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Does the PHP style behaviour for casting when doing a mathematical operation

namespace HH\Lib\Legacy_FIXME;

function cast_for_arithmetic(
  mixed $value,
): dynamic;

That happens under the following situations

  1. null converts to 0
  2. bool converts to 0/1
  3. numeric string converts to an int or double based on how the string looks.
  4. non-numeric string gets converted to 0
  5. resources get casted to int

Parameters​

  • mixed $value

Returns​

  • dynamic