Re: STL map or hash map using struct as data and find it

kl <>
Mon, 31 Dec 2007 02:58:35 -0800 (PST)
On 31 Dec, 11:48, kl <> wrote:

Sorry I accidantly clicked on the send button.


I'm trying to learn some STL using map or hash_map would maybe even
better to use but I don't really know how to find a specific struct
depending on a DWORD value that is in range of two DWORD values (see
below for more).

So what I trying to achieve is creating a look up table of a IP adress
with a start adress (a DWORD value) and a end adress (a DWORD
value) which I would like to look up to the get the Country name
using a specific IP adress (also in DWORD) which is random access to
the table.

It is easy to use vector, linked list but I would like to try to use
map or hash map for more effecient way to look up or at least test it
out to compare some.

The code is basicly looks like this:

//Struct definition
        DWORD startIP; //IP start adress in DWORD which is alw=

ays unique

        DWORD endIP; //IP end adress in DWORD which is alwa=

ys unique

        char COUNTRYNAME[45]; //Country name like England, Germany=




typedef map <DWORD, IPCOUNTRY> mIPC;
mIPC mIPcountry;

//Initilize the map when and call this function during start up
void initilizeMap()

               //read data from file and insert it into a =


        IPCOUNTRY g_structIP;
        FILE *fp=NULL;
        fp=fopen("ipcountry.dat", "rb");

                while( !feof( fp ) )
                        if(fread(&g_structIP, size=

of(g_structIP), 1, fp)!=0)



ntry[g_structIP.startIP] = g_structIP;



 Here is a more correct comapare function:

 struct compareIPC
   bool operator()(const IPCOUNTRY* ipc1, const IPCOUNTRY* ipc2) const
         if((ipc2.startIP>=ipc1.startIP) && (ipc2.startIP <=
        return true;
    return false;


 //This function will be called with IPaddress set and set the
// countryname depending which country it belongs
 //to using the map look up table
 int lookupCountryName(DWORD IPadress, char *countryname)
    //ok here I'm lost what I should exactly do

    tempIPC.startIP = IPadress;
    tempIPC.endIP = IPadress;

    mIPC::iterator mIPCbegin = mIPcountry.begin();
    mIPC::iterator mIPCend = mIPcountry.end();

    //I would do something like this but also include the tempIPC to
find the correct item

    mIPC::iterator iterResult = find_if(mIPCbegin,

    //code to get the result and set the country name

    return 0;

I tried my best to explain what I'm trying to do and
hopefully some one can shed some light of this.


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