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trim

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.

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().

Guide​

Parameters​

  • string $string
  • ?string $char_mask = NULL

Returns​

  • string

Examples​

$result = Str\trim("example_string    ");
echo($result);
//result: "example_string"

$result = Str\trim("   example_string  ");
echo($result);
//result: "example_string"