QGIS/resources/function_help/json/strpos

{
  "function": "strpos",
  "description": "Return the first matching position of a substring within another string, or -1 if the substring is not found.",
  "arguments": [ {"arg":"haystack","description":"string that is to be searched"},
                 {"arg":"needle","description":"string to search for"}],
  "examples": [ { "expression":"strpos('HELLO WORLD','WORLD')", "returns":"6"},
  { "expression":"strpos('HELLO WORLD','GOODBYE')", "returns":"-1"}
  ]
}