(This question is for those who have read the optional section “The putback Member Function.”) The putback member function “puts back” a symbol into an input stream. Does the symbol that is put back...

(This question is for those who have read the optional section “The

putback Member Function.”) The putback member function “puts back”

a symbol into an input stream. Does the symbol that is put back have to

be the last symbol input from the stream? For example, if your program

reads an 'a' from the input stream, can it use the putback function to put

back a 'b', or can it only put back an 'a'?