This API is part of the Hack Standard Library, not HHVM itself.
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This function is available as Str\trim() in Facebook's www repository.

Returns the given string with whitespace stripped from the beginning and end


namespace HH\Lib\Str;

function trim(
  string $string,
  ?string $char_mask = null,
): string;

If the optional character mask isn't provided, the following characters will be stripped: space, tab, newline, carriage return, NUL byte, vertical tab.

To only strip from the left, see Str\trim_left(). To only strip from the right, see Str\trim_right().


  • string $string
  • ?string $char_mask = null