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one key, multivalued map

csstudent123 (409)
#include <iostream>
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#include <string>
#include <map>
#include <iomanip>
#include <deque>

using namespace std;

int main(){
    //my key is int but i need three values with it of type int, string and char
    map<int, int, string, char> table;
   // ????? how do I do this?
     table[1]=4;
    table[1]="J1"; 
    //.......

    return 0;

}


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//trying this also

using namespace std;
    struct t_info{
        int seats;
        string id;
        bool occupied;

    };

using namespace std;

int main(){



    map<int, t_info> table;
    table[1]=//???;

    return 0;

}
Last edited on
MikeyBoy (5631)
Your second code snippet looks like way to go, to me.
andywestken (4094)
The struct approach is good (though I think a class would be better!)

To add the value to the map you can use a number of approaches, such as:

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#include <iostream>
#include <string>
#include <map>
using namespace std;

struct t_info{
    int seats;
    string id;
    bool occupied;
};

int main(){
    map<int, t_info> table;

    // temp variable, setting members
    cout << "add example 1 (key = 3)\n";
    t_info info_3;
    info_3.seats    = 4;
    info_3.id       = "example 1";
    info_3.occupied = false;
    table[3] = info_3;

    // temp variable, brace initialized
    cout << "add example 2 (key = 8)\n";
    t_info info_8 = {12, "example 2", true};
    //t_info info_8{12, "example 2", true}; // alternative form for C++11
    table[8] = info_8;

#if __cplusplus > 199711L
    // brace initialize (C++11 and newer)
    cout << "add example 3 (key = 14)\n";
    table[14] = t_info({3, "example 3", true});
#else
    cout << "skip example 3 as needs C++11\n";
#endif

    // map::insert gives more control then []
    //
    // Note C++11 allows to use auto for insert's return type here, but spelling
    // things out so can see what's up)

    cout << "add example 4 (key = 3)\n";
    // try to insert new, blank entry
    pair<map<int, t_info>::iterator, bool> ret_3 = table.insert(make_pair(3, t_info()));
    if(!ret_3.second) {
        cout << "insert failed for 3 -- duplicate key!\n";
    } else {
        // would complete entry here if insert succeeded...
    }

    cout << "add example 4 (key = 29)\n";
    // try to insert new, blank entry
    pair<map<int, t_info>::iterator, bool> ret_29 = table.insert(make_pair(29, t_info()));
    if(!ret_29.second) {
        cout << "insert failed for 29 -- duplicate key!\n";
    } else {
        t_info& new_info = ret_29.first->second; // get reference to newly inserted entry
        new_info.seats    = 180;
        new_info.id       = "example 4";
        new_info.occupied = false;
    }

    cout << "\n";

    // list all entries
#if __cplusplus > 199711L
    for(const auto pr : table) {
        int           key  = pr.first;
        const t_info& info = pr.second;
        cout << "[" << key << "]\n"
             << "seats    = " << info.seats    << "\n"
             << "id       = " << info.id       << "\n"
             << "occupied = " << info.occupied << "\n"
             << "\n";
    }
#else
    map<int, t_info>::iterator i = table.begin();
    while(i != table.end()) {
        int           key  = (*i).first;
        const t_info& info = (*i).second;
        cout << "[" << key << "]\n"
             << "seats    = " << info.seats    << "\n"
             << "id       = " << info.id       << "\n"
             << "occupied = " << info.occupied << "\n"
             << "\n";
        ++i;
    }
#endif

    return 0;
}


And more if you add a constructor(s).

Andy
Last edited on
csstudent123 (409)
thanks andy. It works, but I will have to develop my code more...
Duthomhas (13212)
+1 with the class idea. A simple constructor makes life so much easier.

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struct t_info {
    int seats;
    string id;
    bool occupied;

    t_info( int seats = 0, const string& id = string(), bool occupied = true ):
        seats( seats ), id( id ), occupied( occupied )
        { }
};
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    map <int, t_info> classrooms;

    classrooms.emplace( 13728, 20, "Elemental Biology 104 Lab" );
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