Finds the index of the first occurrence of any of the specified strings in this char sequence,
starting from the specified startIndex and optionally ignoring the case.
true to ignore character case when matching a string. By default
An index of the first occurrence of matched string from strings or -1 if none of strings are found.
To avoid ambiguous results when strings in strings have characters in common, this method proceeds from
the beginning to the end of this string, and finds at each position the first element in strings
that matches this string at that position.