QGIS/resources/function_help/json/op_regex

{
  "name": "~",
  "type": "operator",
  "groups": ["Operators"],
  "description": "Performs a regular expression match on a string value. Backslash characters must be double escaped (e.g., \"\\\\\\\\s\" to match a white space character).",
  "arguments": [
        { "arg": "string", "description": "A string value" },
        { "arg": "regex", "description": "A regular expression. Slashes must be escaped, eg \\\\\\\\d." }
  ],
  "examples": [
	{ "expression":"'hello' ~ 'll'", "returns":"1"},
	{ "expression":"'hello' ~ '^ll'", "returns":"0"},
	{ "expression":"'hello' ~ 'llo$'", "returns":"1"},
	{ "expression":"'abc123' ~ '\\\\\\\\d+'", "returns":"1"}
  ]
}