map access outside class

[gauravkr]

Hi All,
I'm new to C++. I need some help regarding the usage of map STL container. I've declare map proteinData in the below header file. ProteinData contains key as integer and value as a struct.
#ifndef _READFILE_H_
#define _READFILE_H_
#include<string>
#include<vector>
#include<map>

using namespace std;

class Readfile{

private:
string str;
vector <string> goArray;
vector <string> strArray;
vector <string> phyIntArray;
vector <string> subArray;
vector <string> proArray;
/* member function */
void processString(string str);
void processGoId(string);
void processPhysicalInt(string);
// void processMetabolicInt(string);

public:
typedef struct Info{
string uniprotID;
vector <string> goId;
vector <string> phyInt;
};

map <int,struct Info> proteinData;
map <int,struct Info>::iterator it;

Readfile(string file);//constructor

};
#endif

Can any one help me how to access map outside the class defination.


Thanks in advance

[jsmith]

Readfile f( "foo.txt" );

f.proteinData // whatever here;

really not a good idea to hold an iterator as a class data member.

[gauravkr]

Thank jsmith for your reply...

Readfile *myfile = new Readfile("foo.txt");
cout << myfile->proteinData << endl;

This is showing an error:
error: no match for ‘operator<<’ in ‘std::cout << myfile->Readfile::proteinData’

As per your suggestion how i should represent an iterator, so that i can access the data inside map outside its class defination....

Thanks once again.

[gauravkr]

i'm able to get the size of the map container proteinData, shown in the below code.

Readfile *myfile=new Readfile('foo.txt');
cout << "this is iterator:" << endl;
cout << myfile->proteinData.size()<< endl;

for(myfile->it=myfile->proteinData.begin(); myfile->it=myfile->proteinData.end();myfile->it++){
cout << myfile->it->first << endl;
}

but couldn't access the iterator defined inside the class, giving an error message

could not convert ‘(myfile->Readfile::it <unknown operator> ((const std::_Rb_tree_iterator<std::pair<const int, Readfile::Info> >&)((const std::_Rb_tree_iterator<std::pair<const int, Readfile::Info> >*)(& myfile->Readfile::proteinData.std::map<_Key, _Tp, _Compare, _Alloc>::end [with _Key = int, _Tp = Readfile::Info, _Compare = std::less<int>, _Alloc = std::allocator<std::pair<const int, Readfile::Info> >]()))))’ to ‘bool’.

I think there is something wrong with defining the iterator inside class as suggested by jsmith.

Can anyone help with this.......

[kbw]

There are many reasons not to store an iterator in your class.
1. Some class operation may invalidate the iterator.
2. Using a local iterator contrains the object to be used by one client, which is unncessary and probably wrong.

You can traverse the map as:

for (map<int, Readfile::Info>::const_iterator p = myfile->proteinData.begin(); p != myfile->proteinData.end(); ++p)
    std::cout << p->first << std::endl;

[gauravkr]

Thanks kwb, it is very helpful .....