Thread: Txt file and data storage

Originally Posted by radnik

Can someone please help me with this stringstream. Just give me a good link if you know it or explain it to me how to parse integers from string with it please.

A stringstream works just like an input or output stream. So we could do something like this:

Code:

#include <sstream>

int main()
{
    std::stringstream ss;

    ss << "100 200 300";

    int x;
    while(ss >> x)
        std::cout >> x >> std::endl;
    return 0;
}

This would give you an output of
100
200
300

--
Mats

stringstreams are a kind of streams, therefore the interface and usage is practically the same as cout, cin and fstreams.

The difference from file streams is that they don't work on a file, but on a string. So, in the constructor you don't specify a file name but a string.

Code:

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

using namespace std;

int main()
{
    string s("10 23 -3 18 9");
    stringstream ss(s);
    int n;
    while (ss >> n) {
        std::cout << n << '\n';
    }
}

I'm stuck again. Now when i do something like:

Code:

string tmp;
		
getline(dat, tmp);
stringstream stmp(tmp);

i have stringstream stmp with one line of numbers from txt file. But how do i read stringstream and store data in x and y coordinates. I understand the simple example that you gave me, but have no idea on how to do this
Is there a way to test end of stringstream in wile loop or something similar??

This line in both mine and matsp's example tests for end of stringstream in exactly the same way you'd check for end of user input with std::cout (Ctrl + Z) and end of file if simply reading integers from a file.

Code:

while (ss >> n)

You can read two variable at a time:

Code:

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

using namespace std;

int main()
{
    string s("10 23 -3 18 9 100 83 29 1 -1");
    stringstream ss(s);
    int n, m;
    while (ss >> n >> m) {
        std::cout << n << ' ' << m << '\n';
    }
}

However, it is somewhat hard to detect problems while parsing the line (e.g odd number of values), so it just assumes original input is good.

Thanks, that helped a lot. What do you suggest me to do on writing numbers of one path in vector Path. Since i don't set it's size (for logical reasons) i can't use something like:

Code:

while (stmp >> x >> y) {
			
			//cout <<"broj is smtp"<<br<<"referenca od p"<<pp<<endl;
			
				t[pp].x=x;
				t[pp].y=y;
				pp++;
	}

What would be my other options? I know how i can count lines in text and in that way set the size of vector Collection of paths. But how can i count numbers per line?? As a matter of fact even if i could count them not every line has the same amount of numbers so this approach is no good. Suggestions please.

The good thing about vectors is that you don't need to know how much data you are going to store beforehand: push_back.

I know that, but when i read two values x and y how can i do bush back. How can i know that it will read the x value in vetor.x and y in vector.y?So when i read the values from file like this:

Code:

while (stmp >> x >> y) {
			
				//cout <<"broj x	"<<x<<"	broj y	"<<y<<"	broj pp	"<<pp<<endl;

how can i store it in vector of classes Koord?:

Code:

class Koord {		//varijabla vrijednosti koordinatnih tocaka x i y

	public:
		double x;
		double y;
		
	};
	typedef vector<Koord>Tocke;		//skup tocaka jednog puta
	typedef vector<Tocke>Putovi;		//svi putovi mape

I know that i will fill "collectionofpaths" with trajektorije.push_back(t); (Putovi trajektorije;, Tocke t), as you said me to do it earlier in this topic.

I suggest that you format your code properly, and more importantly, use English. You can always convert them to your natural language later, but when asking for help in a message board community that is pre-dominantly English, write in English.

It would also help if you divided your code into well named functions. This would allow you to test a particular function to see if it is working, and thus become confident that if there is a problem, it most likely lies elsewhere. This divide and conquer approach will help you debug your code, and help others understand it. Likewise, use meaningful variable names, not t and p.

Code:

	ifstream dat (argv[1]);
	if (!dat) {
		cerr << "Nije moguce otvoriti zadanu datoteku "<< argv[1]<<endl;
	}

I think you want "if(!dat.is_open())" there.

Anyway. I'm not too sure what you're trying to do -- I haven't read the whole thread -- but perhaps this will be helpful:

Code:

#include <iostream>
#include <vector>

class pos {
public:
    int xp, yp;
    pos() {}
    pos(int x, int y) : xp(x), yp(y) {}
};

int main() {
    std::vector<pos> v(10);
    v.push_back(pos(2, 3));
    v.push_back(pos(5, 4));

    return 0;
}

You are right laserlight. Sorry for the Croatian language. I will post English version now. I don't know what you mean by formatting of code because all of the "layout" was done by my editor i didn't touch a thing. I will put all of the code in functions later.
Dwks thank you. That helped a lot. But still while printing values of paths vector i get some memory junk in between my real values. Like this:

Code:

        
        12 14
        15 17              PATH 1
        987 234
        23 45

        
         3.60739e-313 4.95672e-270
        1.54972e-312 12
        14 15
        17 987
        234 23                           SOME MEMORY JUNK AND REPEATED VALUES FROM PATH 1
        12 14
        15 17
        987 234
        23 45

        
        1 2
        65 34
        56 34                     PATH 2
        12 78
        23 987

I'll post new code with English and deleted unnecessary parts:

Code:

#include <iostream>
#include <cstdlib>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>
using namespace std;

class Coord {		//values of coordinates (x,y)

	public:
		double xt;
		double yt;
		
		Coord(){};
		Coord(double x, double y) : xt(x), yt(y) {}; 
		
	};
	
typedef vector<Coord>Dots;		//collection of coordinates for one path (one line in txt file is one path)
typedef vector<Dots>Paths;		//collection of all paths

int main(int argc, char* argv[])
{
	
	Paths trajectories;
	Dots pairs;
	int i,j;
	
	if (argc == 2) {	
	
	ifstream dat (argv[1]);
	if (!dat) {
		cerr << "Given file cannot be opened "<< argv[1]<<endl;
	}
	
	while (!dat.eof()) {
		
		string tmp;
		double x,y;
		
		getline(dat, tmp);
		stringstream stmp(tmp);

		int p=-1;
		int &pp = p;
		
		while (stmp >> x >> y) {
				
				p++;
				cout <<"counter pp="<<pp<<"\n"<<"number x	"<<x<<"	number y	"<<y<<endl;
			
				pairs.push_back(Coord(x,y));

				cout <<"number x inside vector	"<<pairs[pp].xt<<"	number y inside vector	"<<pairs[pp].yt<<endl;
				// the lines for printing are just for testing because i had some problems here
		}
		
		trajectories.push_back(pairs);	
	}	
}	
else if (argc < 2) {
		cout << "Error while running program" <<endl;
		cout << "Usage: eg_decomposition <file_name>" <<endl;
	}
else {
		cerr << "Too much parameters" << endl;
		exit (1);
	}	
		
// printing of all paths		
for(i=0; i < trajectories.size(); i++) {
	for (j=0; j < pairs.size(); j++)
		cout << '\t' << trajectories[i][j].xt <<' '<<trajectories[i][j].yt << endl; 
				
	}
	
return 0;
}

If i'm right the repeating of numbers occurs because i never clear my pairs vector so those old coordinates remain in the vector. How can i solve this? I've tried this:

Code:

while (stmp >> x >> y) {
				
				p++;
				cout <<"counter pp="<<pp<<"\n"<<"number x	"<<x<<"	number y	"<<y<<endl;
			
				tmp_pairs.push_back(Coord(x,y));

				cout <<"number x inside vector	"<<tmp_pairs[pp].xt<<"	number y inside vector	"<<tmp_pairs[pp].yt<<endl;
				// the lines for printing are just for testing because i had some problems here
		}
		
		pairs=tmp_pairs;
		trajectories.push_back(pairs);
		tmp_pairs.clear();

But then when i tried to print the values i got nothing. Why is this happening if i cleared the temporary vector tmp_pairs? I presume that i can't do something like pairs=tmp_pairs;. How could i do this the other way? I tried the vector copying method with vector<Coord> pairs(tmp_pairs) but still got the same results Is there any method of appending values of one vector to another?