How to add list items in the following manner?

Question

Hi

I Have a list that contains dbfile,paths and i need to add them to a map inorder to get corresponding values. my LIST contains items as like

star
e:\data\star.mdf
e:\data\star.ldf
kiran
e:\data\kiran.mdf
e:\data\kiran.ldf  
hai
e:\data\hai.mdf
e:\data\hai.ldf

Now i need to insert them by populating a list as specified format

map<string,list<string>>
     |           |
    \/          \/
   databasename   paths info

how can i do this.

Plz help me

Answer 1

You could write the following:

std::list tempList;
tempList.push_back("e:\data\star.mdf");
tempList.push_back("e:\data\star.ldf");
m.insert(std::make_pair("star", tempList));

Note however that the tempList will be copied upon inserting. You might consider this to be an unacceptable performance overhead, which might be solved by using a smart pointer to the list. For example:

std::map>> m;

Answer 2

When you read a string, like "star" (we'll assume into s), createa map entry:

mymap.insert( std::make_pair( s, list <string>() ) );

Now you will be reading directory names, into say d. As you have just created the entry, it's safe to use map's operator[]:

mymap[s].push_back( d );

Answer 3

I suppose that is what you want to do: You need to go through the file line-by-line using getline(), than you convert the buffer you used for getline to a string and check with a regular expression if it is a path or a datbasename (you might make your file format more verbose to express this more clearly or you use XML). Then you call the appropriate function to add to the map. In pseudocode with the assumption that there are only to paths per db:

infile.open(FILENAME);
while(infile.good()) {
getline(infile, buffer, blength)
string dbName = buffer
for(int i = 0; i < 2; i++) getline() and to string addStuffToMap();

Too lazy to write a working version right now...

Answer 4

What you need is a map of names (string) to a list of paths (string). All you need to do is declare exactly that: std::map< std::string, std::list< std::string> >. Easy as pie :-)

Try this:

#include <list>
#include <map>
#include <string>


int main()
{
    std::map<std::string,std::list<std::string> >     dbMap;

    dbMap["star"].push_back("e:\data\star.mdf");
    dbMap["star"].push_back("e:\data\star.ldf");

    dbMap["kiran"].push_back("e:\data\kiran.mdf");
    dbMap["kiran"].push_back("e:\data\kiran.ldf");

    dbMap["hai"].push_back("e:\data\hai.mdf");
    dbMap["hai"].push_back("e:\data\hai.ldf");
}