str

    The address of the character string that provides the input text
    to sscanf.

 format_spec

    A pointer to a character string that contains the format
    specification.

  . . .

    Optional expressions whose resultant types correspond to
    conversion specifications given in the format specification.

    If no conversion specifications are given, you can omit the input
    pointers. Otherwise, the function calls must have at least as
    many input pointers as there are conversion specifications, and
    the conversion specifications must match the types of the input
    pointers.

    Conversion specifications are matched to input sources in left-
    to-right order. Excess input pointers, if any, are ignored.