anyone can solve this old problem?

[easonlol]

http://www.cplusplus.com/forum/beginner/26873/
I came across the same problem with the above link, it seems that that problem hasn't been solved yet. Anyone can help me?

[kbw]

It seems straight forward enough. What part of the problem are you having difficulty with?

[easonlol]

question：write a program to compare whether a vector<int> contains the same elements as a list<int>.
my codes:

#include <iostream>
#include <vector>
#include <list>
using namespace std;

int main()
{
	vector<int> ivec;
	list<int> ilst;
	int ival;
	cout << "Enter several numbers for vector<int>:" << endl;
	while (cin >> ival)
	{
		ivec.push_back(ival);
	}
	cin.clear();
	cin.sync();	
	cout << "Enter several numbers for list<int>:" << endl;
	while (cin >> ival)
	{
		ilst.push_back(ival);
	}
	
	if (ivec.size() != ilst.size())
	{
		cout << "ivec != ilst" << endl;
		return -1;	
	}
	
	vector<int>::iterator vit = ivec.begin();
	list<int>::iterator lit = ilst.begin();
	
	while (vit != ivec.end())
	{
		if (*vit != *lit)
		{
			cout << "ivec != ilst" << endl;
			return -1;
		}
		else
		{
			++vit;
			++lit;
		}
	}
	cout << "ivec == ilst" << endl;
	return 0;
}

on mac ox x lion, I use the gcc compiler and the output:

Enter several numbers for vector<int>:
1
2
3
// I entered control + D here
Enter several numbers for list<int>:
ivec != ilst

I have no opportunity to input list<int> container!
but this program runs well on windows using MinGW compiler.
how to solve this problem? thx in advance!

[kbw]

If you can put all the numbers on the same line, you can read the whole line and process that. For example:

#include <iostream>
#include <sstream>
#include <string>

int main()
{
    std::string line;

    std::cout << "Please enter numbers for vector on the same line" << std::endl;
    std::getline(std::cin, line);
    {
        std::istringstream is(line);
        int value;
        while (is >> value)
            // append value to the vector
            ;
    }

    std::cout << "Please enter numbers for list on the same line" << std::endl;
    std::getline(std::cin, line);
    {
        std::istringstream is(line);
        int value;
        while (is >> value)
            // append value to the list
            ;
    }

    return 0;
}

[easonlol]

if you can put all the numbers on the same line, you can read the whole line and process that. For example:
#include <iostream>
#include <sstream>
#include <string>

int main()
{
std::string line;

std::cout << "Please enter numbers for vector on the same line" << std::endl;
std::getline(std::cin, line);
{
std::istringstream is(line);
int value;
while (is >> value)
// append value to the vector
;
}

std::cout << "Please enter numbers for list on the same line" << std::endl;
std::getline(std::cin, line);
{
std::istringstream is(line);
int value;
while (is >> value)
// append value to the list
;
}

return 0;
}

I know its an alternative method, but I still want to know what the problem with my program?

[Peter87]

If you end the stream with control + D I'm not sure if you can enter more input later. Note that cin.sync(); doesn't do anything with gcc so you could try to use something else like cin.ignore(numeric_limits<streamsize>::max(), '\n');

[easonlol]

Actually, even I use
cin.ignore(numeric_limits<streamsize>::max(), '\n');
instead of
cin.sync();
the problem is still the same...
It's driving me crazy

[Cubbi]

Like Peter said, you've ended the input stream. The system has no reason to expect further input to appear. Imagine you were redirecting a file into the standard input of the program -- there's no way to redirect *two* files.

On the other hand, Mac appears to be alone in this: I just ran your program on Linux (gcc), Solaris (CC), AIX (xlc), and HP-UX (acc), and they all accept further input after cin.clear(). I don't have a Mac system, but give cin.sync_with_stdio(false); a try.

(and don't use cin.sync(), of course)

[JLBorges]

> Mac appears to be alone in this

Mac is FreeBSD 5.5; I guess all the BSDs would behave in the same way.

[kbw]

I just tested it.

OS X (Lion) and FreeBSD (7.2) have the same behaviour, cin cannot be cleared.

It's fine on Linux.

[JLBorges]

In the BSDs, fpurge(stdin) ; is used to flush stdin (or any input stream).
http://www.freebsd.org/cgi/man.cgi?query=fpurge&apropos=0&sektion=0&manpath=FreeBSD+9.0-RELEASE&arch=default&format=html

Apparently, the GNU libstdc++ doesn't use it.