C++: Help output nested strings

[Diane]

Could you please explain me how can I output nested strings?

Here is an example:

"adsd{rf[dfF]km}xcv"

The output should start from the inner parentheses, such as:

dfF
rfkm
adsdxcv
Thanks!

[Victor Bazarov]

Diane wrote:

Could you please explain me how can I output nested strings?

Here is an example:

"adsd{rf[dfF]km}xcv"

The output should start from the inner parentheses, such as:

dfF
rfkm
adsdxcv

This isn't a C++ problem. You need to build those strings.
It's a programming problem. What you have is a stack of
strings represented in a certain grammatical form. What you
need to do is to convert one representation into the other
and then output the other (the stack of strings). How to
convert one into the other is not a _language_ problem. You
are supposed to come up with an algorithm.

Come back once you have the algorithm and we'll help you put
it into C++ terms. Of course, if you have any C++ experience
at all, try writing your program and then we can help you get
it to work.

Also, as I see it, the string building function should probably
be recursive. It should start building its string either at the
beginning or right after getting an opening bracket/brace/paren
and end with the matching closing bracket/brace/paren or at the
end of the input. Once the function built the string it can
simply output it.

V
--
Please remove capital As from my address when replying by mail

[Diane]

Thanks for your reply Victor!

Here is what I tried to do, but it doesn't seem to work properly.
Any suggestions?

int main()
{
Stack s;
char symbol;
int counter = -1;
char match;

// read all characters from keyboard and push them in the stack
while((symbol=cin.get()) != '\n')
{
s.push(symbol);
counter++;
}
//scan the stack to output the nested strings
for(int i=0; i<counter; i++)
{

if(symbol == '{' || symbol == '(' || symbol == '[')
{
cout << "\n";
match = symbol;
}

if(symbol == '}' || symbol == ')' || symbol == ']')
{
if( (symbol == '}' && match == '{') || (symbol == ')' &&
match == '(')
|| (symbol == ']' && match == '[') )
{
s.pop();
}
}

}

return 0;

}

[Victor Bazarov]

Diane wrote:

Here is what I tried to do, but it doesn't seem to work properly.
Any suggestions?
You need to fix it.

[...]
if(symbol == '{' || symbol == '(' || symbol == '[')
{
cout << "\n";
Wouldn't it make more sense to do all output at the _closing_
character?
match = symbol;
}

if(symbol == '}' || symbol == ')' || symbol == ']')
{
if( (symbol == '}' && match == '{') || (symbol == ')' &&
match == '(')
|| (symbol == ']' && match == '[') )
{
s.pop();
... and you're losing the string here instead of outputting it...
}
}

V
--
Please remove capital As from my address when replying by mail

[Daniel T.]

In article <11*********************@f14g2000cwb.googlegroups. com>,
"Diane" <fr*********@hotmail.com> wrote:

Could you please explain me how can I output nested strings?

Here is an example:

"adsd{rf[dfF]km}xcv"

The output should start from the inner parentheses, such as:

dfF
rfkm
adsdxcv

Paste the code below in your program (replace what you have) and play
with the code in the "parse_string" function until it works. Instead of
sending output to "cout" send it to "os".

void parse_string( const string& s, ostream& os ) {
// change the code in this method
os << s;
}

int main() {
string test( "hello" );
stringstream ss;
parse_string( test, ss );
assert( ss.str() == test );

test = "Good[hello]by";
ss.str( "" );
parse_string( test, ss );
assert( ss.str() == "hello\nGoodby" );

test = "Good(hello)by";
ss.str( "" );
parse_string( test, ss );
assert( ss.str() == "hello\nGoodby" );

cout << "working\n";
}

--
Magic depends on tradition and belief. It does not welcome observation,
nor does it profit by experiment. On the other hand, science is based
on experience; it is open to correction by observation and experiment.

[Asfand Yar Qazi]

Daniel T. wrote:

In article <11*********************@f14g2000cwb.googlegroups. com>,
"Diane" <fr*********@hotmail.com> wrote:

Could you please explain me how can I output nested strings?

Here is an example:

"adsd{rf[dfF]km}xcv"

The output should start from the inner parentheses, such as:

dfF
rfkm
adsdxcv

Paste the code below in your program (replace what you have) and play
with the code in the "parse_string" function until it works. Instead of
sending output to "cout" send it to "os".

void parse_string( const string& s, ostream& os ) {
// change the code in this method

I recommend the boost::spirit framework to create a simple parser. Question
for the OP: do you want to output strings such as
"abc{xyz}ijk{ABC[lmn]dkd[123]}uiop{[sdf]}"? First you must define a set of
rules the matched strings must adhere to (number of nestings allowed, etc.)
before you can do anything.
os << s;
}

<snip>

--
To reply, take of all ZIGs !!

[Diane]

What does the parse_string method suppose to do?

I think that the stringstream works only with whitespaces. What if I
have other delimiters?

[Daniel T.]

In article <11**********************@g44g2000cwa.googlegroups .com>,
"Diane" <fr*********@hotmail.com> wrote:

What does the parse_string method suppose to do?
In the long term, it's supposed to output nested strings like your
example. For now, it's supposed to make the tests in main pass.

Notice that the last line in 'main' is [cout << "working\n";] Your job
is to put code in "parse_string" until the program outputs "working"
Once you have done that, you will be one step closer to having your
assignment done.
I think that the stringstream works only with whitespaces. What if I
have other delimiters?

For your purposes, stringstream works exactly like cout, except it
outputs to a string rather than the screen.
--
Magic depends on tradition and belief. It does not welcome observation,
nor does it profit by experiment. On the other hand, science is based
on experience; it is open to correction by observation and experiment.

[Diane]

Thanks!

[Daniel T.]

In article <11**********************@g47g2000cwa.googlegroups .com>,
"Diane" <fr*********@hotmail.com> wrote:

Thanks!

Check your "fr*********@hotmail.com" account email...

--
Magic depends on tradition and belief. It does not welcome observation,
nor does it profit by experiment. On the other hand, science is based
on experience; it is open to correction by observation and experiment.