Problem C
TEX Quotes
TEX is a typesetting language developed by
Donald Knuth. It takes source text together with a few typesetting instructions
and produces, one hopes, a beautiful document. Beautiful documents use
double-left-quote and double-right-quote to delimit quotations, rather than the
mundane " which is what is provided by most keyboards. Keyboards typically do
not have an oriented double-quote, but they do have a left-single-quote ` and a
right-single-quote '. Check your keyboard now to locate the left-single-quote
key ` (sometimes called the "backquote key") and the right-single-quote key '
(sometimes called the "apostrophe" or just "quote"). Be careful not to confuse
the left-single-quote ` with the "backslash" key \. TEX lets the user type two
left-single-quotes `` to create a left-double-quote and two right-single-quotes
'' to create a right-double-quote. Most typists, however, are accustomed to
delimiting their quotations with the un-oriented double-quote ".
If the
source contained "To be or not to be," quoth the bard, "that is the question."
then the
typeset document produced by TEX would not contain the desired form: "To be or
not to be," quoth the bard, "that is the question." In order to produce the
desired form, the source file must contain the sequence: ``To be or not to be,'' quoth the bard, ``that is the question.''
You
are to write a program which converts text containing double-quote (")
characters into text that is identical except that double-quotes have been
replaced by the two-character sequences required by TEX for delimiting
quotations with oriented double-quotes. The double-quote (") characters should
be replaced appropriately by either `` if the " opens a quotation and by '' if
the " closes a quotation. Notice that the question of nested quotations does not
arise: The first " must be replaced by ``, the next by '', the next by ``, the
next by '', the next by ``, the next by '', and so on.
Input will
consist of several lines of text containing an even number of double-quote (")
characters. Input is ended with an end-of-file character. The text must be
output exactly as it was input except that:
- the first " in each pair is replaced by two ` characters: `` and
- the second " in each pair is replaced by two ' characters: ''.
Sample Input:
"To be or not to be," quoth the Bard, "that
is the question".
The programming contestant replied: "I must disagree.
To `C' or not to `C', that is The Question!"
Sample Output:
``To be or not to be,'' quoth the Bard, ``that
is the question''.
The programming contestant replied: ``I must disagree.
To `C' or not to `C', that is The Question!''