Vector of pointers to class objects dynamic allocation and dellocation

[Gast]

class CSNP{
public:
    static bool checkCorrectMapfile(string line);
// ...
};

[euklid]

• Gugelmoser schrieb:

class CSNP{
public:
    static bool checkCorrectMapfile(string line);
// ...
};

Hi Gugelmoser, thank you so much! would you please explain what kind of miracle this static in the code

static bool checkCorrectMapfile(string line);

did and it worked.why it didn't work without static?

best wishes
euklid

[Gast]

euklid schrieb:

• Gugelmoser schrieb:

class CSNP{
public:
    static bool checkCorrectMapfile(string line);
// ...
};

Hi Gugelmoser, thank you so much! would you please explain what kind of miracle this static in the code

static bool checkCorrectMapfile(string line);

did and it worked.why it didn't work without static?

• I tried with static but checkCorrectMapfile is still not doing what I want this function to do. Even though I have four columns in the map file, it is still saying that:
  "your map file was expected to have 4 columns but this is not the case"
  I do not know why.

best wishes
euklid

class Person
{
    private:
        double weight;

    public:
        Person(double w) : weight(w) {}
        double whats_my_weight() { return weight; };    
};

int main()
{
    /*
        In general, you'll always have to greate an object.
        Look, what sense would it make if you do Person::whats_me_weight()... if you have no person, you can't have any weight.
    */
    Person p(88.5);
    cout << "I weight " << p.whats_my_weight();

    /*
        But sometimes you want a function to be independent from a object... then static comes into play, like in your case.
        You want to call a function with its class name using the scope operator: you want to do CSNP::checkCorrectMapfile(line)
        --> thus you want a function being independent from an object.
    */
}

I hope that helps a bit.

[euklid]

class Person
{
    private:
        double weight;
    
    public:
        Person(double w) : weight(w) {}
        double whats_my_weight() { return weight; };    
};

int main()
{
    /*
        In general, you'll always have to greate an object.
        Look, what sense would it make if you do Person::whats_me_weight()... if you have no person, you can't have any weight.
    */
    Person p(88.5);
    cout << "I weight " << p.whats_my_weight();
    
    
    /*
        But sometimes you want a function to be independent from a object... then static comes into play, like in your case.
        You want to call a function with its class name using the scope operator: you want to do CSNP::checkCorrectMapfile(line)
        --> thus you want a function being independent from an object.
    */
}

I hope that helps a bit.

Thank you so much! I appreciate your explanation!

• I tried with static but checkCorrectMapfile is still not doing what I want this function to do. Even though I have four columns in the map file, it is still saying that:
  "your map file was expected to have 4 columns but this is not the case".
• I found that vector<string> tokens has 0 size. This means there is no stream any more in when I call this function. But I still do not know what to do. I think after line 40 of the code

stringstream line_parser(line);

I should not write

if(CSNP::checkCorrectMapfile(line))

Probably the line has no value any more. However, I still do not know how to solve this problem.

[Gast]

edit: Murks

[euklid]

thank you so much for kind response. it works fine but in this way, I have to open and read the file two times: once when I want for checkCorrectMapfile and once for the function

ostream& operator<<(ostream &out, const CSNP &csnp)

since my file is very large, I am interested to read the file only once to check if the correctness of test.map and then save it as an object of class type.
using the following function.

stream& operator>>(istream& in, CSNP &csnp){
    string line;
    while (getline(in, line) and (!line.size() or line[0] == '#'));
    stringstream line_parser(line);
    if(CSNP::checkCorrectMapfile(line)) // this line is not working
    line_parser >> csnp.nchr >> csnp.snpName >> csnp.allele1 >> csnp.allele2;
    else
        line_parser >> csnp.snpName >> csnp.allele1 >> csnp.allele2;
    if (!line_parser) in.setstate(ios::failbit);
    return in;}

However, it is not working. I have written this problem as a simple example. If anyone could find the solution of the following problem, I would be thankful.
The problem is is written as comments in lines 22, 23 and 27 of the following program

#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<cstdlib>
using namespace std;
int main(){
	string line;
	string name, famName, buff;
	vector<string> tokens;
	cout << " enter your name: ";
	while(cin){
		getline(cin, line);
		if(line=="0")exit(1);
	cout << "your name is: "<< line <<".\n"; 
	stringstream ss(line);
		while (ss>> buff)
		tokens.push_back(buff);
		for(int i=0; i<tokens.size();i++)
			cout <<" "<<tokens[i];
			cout <<endl;
		/* I want to use ss again but it is not working 
		 Is the life time of ss expired now?
		 */
		ss>>name >> famName;
	cout <<"name: " <<name << " and "<<"famName: "<<famName <<".\n";
        // name and famName have  no values assigned. why?       

	}	
return 0;
}

ps: There is no compiling error. Only that name and famName have no values assigned at the end.

[Gast]

Just to clarify:

1. There is a mapfile given just like that:

1 snp1 0 1
3 snp2 0 2
2 snp3 1 1
2 snp4 2 2
3 snp5 1 2

2. You want to check wheather the mapfile is built correctly.

3. You want to read the mapfile and store its content into CSNP-Objects.

4. You want to output all the CSNP-Objects.

Is this what you're trying to do or are we tearing past each other?

[euklid]

Gugelmoser schrieb:

Just to clarify:
1. There is a mapfile given just like that:

1 snp1 0 1
3 snp2 0 2
2 snp3 1 1
2 snp4 2 2
3 snp5 1 2

2. You want to check wheather the mapfile is built correctly.

3. You want to read the mapfile and store its content into CSNP-Objects.

4. You want to output all the CSNP-Objects.

Is this what you're trying to do or are we tearing past each other?

Yes Gugelmoser, you are absolutely right.
[list]
[1] I have a bool parameter with default value false say

bool threeColumns =false

if threeColumns=true, the map file looks like

snp1 0 1
 snp2 0 2
 snp3 1 1
 snp4 2 2
 snp5 1 2

In this case I want that the default value of #nchr is for example 0.

[2]If threeColumns=false, then

1 snp1 0 1
3 snp2 0 2
2 snp3 1 1
2 snp4 2 2
3 snp5 1 2

[3] I want first check for the correct mapfile like I did before and then I want to save them as class a vector of class objects.
[4] The map file is very large at least 10000,000 rows.

int main()
{
  vector<CSNP> genInfo;
  {
    CSNP value;
    ifstream file("test.map");
    while (file >> value)
      genInfo.push_back(value);
  }

where each object CSPP looks like

class CSNP
{
private:
  int nchr;
  string snpName;
  string allele1;
  string allele2;
  friend istream& operator>>(istream& in, CSNP &csnp);
// this I was trying to define like before. 

 };

[Gast]

Well i was bored and that's the result (you're looking for)

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

/*
    mapfile:
        1 snp1 0 1
        3 snp2 0 2
        2 snp3 1 1
        2 snp4 2 2
        3 snp5 1 2
*/

class CSNP
{
    private:
        static bool three_columns; 
        int nchr;
        string snpName;
        string allele1;
        string allele2;

    public:
        static bool checkCorrectMapfile(const string&);
        CSNP() : nchr(0) {}
        friend istream& operator>>(istream& in, CSNP& csnp) 
        {
            if(!three_columns)
            {
                in>>csnp.nchr;
            }
            getline(in,csnp.snpName,' ');
            getline(in,csnp.allele1,' ');
            return getline(in,csnp.allele2);
        }
        friend ostream& operator<<(ostream &out, const CSNP &csnp)
        {
            return out << csnp.nchr << ' ' << csnp.snpName << ' ' << csnp.allele1 << ' ' << csnp.allele2;
        }      
};

bool CSNP::three_columns = false;
bool CSNP::checkCorrectMapfile(const string& mapfile)
{

    ifstream in( mapfile.c_str() );

    if(!in)
    {
        cerr << "could not open mapfile";
        return false;
    }
    else
    {
        vector<string> lines;
        string buffer;

        while( getline(in,buffer) )
        {
            lines.push_back(buffer);
        }

        for(vector<string>::iterator it=lines.begin(); it!=lines.end(); ++it)
        {
            istringstream iss(*it);
            vector<string> tokens;

            while( getline(iss,buffer,' ') )
            {
                tokens.push_back(buffer);
            }

            if(tokens.size() != 3 && tokens.size() != 4)
            {
                cerr << "your mapfile was expected to have either 3 or 4 columns!";
                return false;
            }

            if( !three_columns && tokens.size() == 3)
            {
                three_columns = true;
            }
        }
    }
    cout << "your mapfile is correct!";
    return true;
}

int main()
{
    string mapfile = "...";

    if( CSNP::checkCorrectMapfile(mapfile) )
    {
        ifstream in( mapfile.c_str() );
        vector<CSNP> objects;

        for(CSNP csnp; in >> csnp;)
        {
            objects.push_back(csnp);
            cout << '\n' << csnp;
        }

        // now, every line is stored into a CSNP-Object.
    }

    return 0;
}

To be honest, i don't know wheater the design is or is not good.
Anyhow, reading the file only once... i didn't manage to get any good design for that :(.

[euklid]

thank you so much for your help. I have posted new code which is error free but not efficient.