cpp/experimental/basic string view/find last of

Finds the last character equal to any of the characters in the given character sequence.

@1@Finds the last occurence of any of the characters of in this view, starting at position. @2@Equivalent to. @3@Equivalent to. @4@Equivalent to.

Return value
Position of the last occurrence of any character of the substring, or npos if no such character is found.

Complexity
O( * ) at worst.