STL map testing ??

[ezuzz]

#include <iostream>
#include <ext/hash_map>
#include <string>
#include <map>
#include <stdio.h>
#include <string.h>

using namespace std;

class subInfo{
    public:
        float Weight;
        subInfo(){}
        subInfo(float _w){
            Weight = _w;
        }
        ~subInfo(){}
        bool operator<(const subInfo & rsh){
            return  Weight < rsh.Weight;
        }
};

typedef map<string , subInfo > _hash;

void DeKey(const char* key,int & t, int & t2){

     memcpy(&t,key,sizeof(int));
     memcpy(&t2,key+sizeof(int),sizeof(int));

}

int main(){


    _hash hs;
    _hash::iterator find;

    int tid=1;

    for(int i=1;i<10;i++){

        char *key = new char[8];
        memset(key,0,8);


        memcpy(key,(char*)&tid,4);
        memcpy(key+sizeof(int),(char*)&i,4);

        cout<<"size:"<<sizeof(key)<<endl;
        cout<<"leng:"<<strlen(key)<<endl;

        find=hs.find(string(key));
        if(find == hs.end()){
            subInfo  sub((float)i);
            hs.insert(make_pair(string(key),sub));
            cout<<"key:["<<key<<"]inserted"<<endl;
        }else {

            int j=0,k=0;
            DeKey(find->first.c_str(),j,k);
            cout<<"key:["<<j<<k<<"] founded"<<endl;
            delete[] key;
        }

    }
    cout<<"----------------------------------------------------"<<endl;
    cout<<"hash size:"<<hs.size()<<endl;
    cout<<"----------------------------------------------------"<<endl;

   return 0;
}

// Q1. only one iterm was inserted. what's wrong??
// Q2. when i finished inserting iterm, release key-memory ?

[Mick]

<moved thread>

[Philip Nicoletti]

In a couple places in your loop, you use :

string(key)

This will create a string from the char* key variable, however, it stops
when it sees a NULL (that's how it knows how many characters to
put in the string). I suspect that your first character is NULL. If this
is the case, try something like this:

string sKey(key,key+8);

find=hs.find(sKey);
if(find == hs.end()){
     subInfo  sub((float)i);
     hs.insert(make_pair(sKey,sub));
     cout<<"key:["<<key<<"]inserted"<<endl;
}else {

[Kheun]

1. If you only inserting pairs which the keys are exactly the same. As string is null-terminated, your string becomes "\01". You may try stringstream to generate your key instead.

2. For all memory allocated through new, you have to delete them to avoid memory leak.

#include <iostream>
#include <sstream>
#include <map>

using namespace std;

typedef map<string , subInfo > _hash;

void DeKey(const string& key, int &t1, int &t2)
{
    istringstream in(key);
    in >> t1 >> t2;
}


int main(){

    _hash hs;
    _hash::iterator find;

    int tid=1;

    for(int i=1;i<10;i++){

        ostringstream out;
        out << tid << " " << i;

        string key(out.str());
        cout<<"length:"<<key.length()<<endl;


        find=hs.find(key);

        if(find == hs.end()){
            subInfo  sub((float)i);
            hs.insert(make_pair(key,sub));
            cout<<"key:["<<key<<"]inserted"<<endl;
        }else {

            int j=0,k=0;
            DeKey(find->first,j,k);
            cout<<"key:["<<j<<k<<"] founded"<<endl;
        }

    }
    cout<<"----------------------------------------------------"<<endl;
    cout<<"hash size:"<<hs.size()<<endl;
    cout<<"----------------------------------------------------"<<endl;

   return 0;
}