This API is part of the Hack Standard Library, not HHVM itself.

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.


  • string $string
  • ?string $char_mask = NULL