Nested Boost::unordered_map with std::pair insertion help ..

[Rahul Mathur]

All,

I have having Boost boost::unordered_map nested map calling boost::unordered_map which calls std::map finally.

The LHS (towards RHS) side key for first boost::unordered_map is 'int' type followed by next key being char buffer value of size 10, and key for std::map being again a char buffer value of size 10. So the boost::unordered_map has nested map internally.
I have to insert the char buffer of size 10 (value being either 'ORANGE' or ORD123 as test case) into nested std::pair as defined below. After inserting, I have to search or find the value from char buffer of size 10.

The code as compiled on Linux is -

----
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <boost/unordered_map.hpp>
#include <map>
#include <algorithm>
#include <string>

using namespace std;

#if 0
#pragma pack(push, 2)
struct BookKeeping {
int ABCD;
char Apple_ID [10];
char Apple_NAME[10];
int Price;
int Number;
};
#pragma pack(pop)
#endif

class Name { // buffer of size 10
char str[10];
public:
Name() {
strcpy(str, "");
}
Name(char *s) {
strcpy(str, s);
}
char *get() {
return str;
}
};

bool operator<(Name a, Name b)
{
return strcmp(a.get(), b.get()) < 0;
}

#pragma pack(push, 2)
struct BookKeeping {
int ABCD;
Name Apple_ID;
Name Apple_NAME;
int Price;
int Number;
};
#pragma pack(pop)

BookKeeping *_bkkping;

typedef boost::unordered_map< int, boost::unordered_map< Name, std::map< Name, int > > > _uordmap; // nested boost::unordered_map

class BkKping {
private:
_uordmap * uordmap;

typedef boost::unordered_map< int, boost::unordered_map< Name, std::map< Name, int > > >::iterator _itr_1;
typedef boost::unordered_map< Name, std::map< Name, int > >::iterator _itr_2;
typedef std::map< Name, int >::iterator _itr_3;

public:
BkKping () {
uordmap = new _uordmap ();
}
void Apple ( int abcd, const char * Apple_ID_, const char * Color_, int Price_ );
~BkKping () {
delete uordmap;
}

};

void BkKping::Apple ( int abcd, const char * Apple_ID_, const char * Color_, int Price_ ) {

uordmap->insert( std::pair< int, std::pair< Name, std::pair< Name, BookKeeping &> > > ( _bkkping->ABCD , _bkkping->Apple_ID, _bkkping->Apple_NAME, *_bkkping) ); // nested std::pair<> insertion
}

int main () {

int abcd;
const char * Apple_ID_;
const char * Color_;
int Price_;

BkKping book;
book.Apple( abcd, Apple_ID_, Color_, Price_);

}
-----

The error message is -

---
hello.cpp: In member function âvoid BkKping::Apple(int, const char*, const char*, int)â:
hello.cpp:76: error: no matching function for call to âstd::pair<int, std::pair<Name, std::pair<Name, BookKeeping&> > >::pair(int&, Name&, Name&, BookKeeping&)â
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/stl_pair.h:83: note: candidates are: std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = int, _T2 = std::pair<Name, std::pair<Name, BookKeeping&> >]
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/stl_pair.h:79: note: std::pair<_T1, _T2>::pair() [with _T1 = int, _T2 = std::pair<Name, std::pair<Name, BookKeeping&> >]
/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/bits/stl_pair.h:68: note: std::pair<int, std::pair<Name, std::pair<Name, BookKeeping&> > >::pair(const std::pair<int, std::pair<Name, std::pair<Name, BookKeeping&> > >&)
--

I have created a class buffer to read size 10.

Please help.

P.S: No issue with Boost compilation, simply looking for proper semantic call for nested std::pair<>.

[Victor Bazarov]

On 2/20/2014 7:32 AM, Rahul Mathur wrote:
> I have having Boost boost::unordered_map nested map calling
boost::unordered_map which calls std::map finally.
>
> The LHS (towards RHS) side key for first boost::unordered_map is
> 'int'
type followed by next key being char buffer value of size 10, and key
for std::map being again a char buffer value of size 10. So the
boost::unordered_map has nested map internally.
> I have to insert the char buffer of size 10 (value being either
'ORANGE' or ORD123 as test case) into nested std::pair as defined below.
After inserting, I have to search or find the value from char buffer of
size 10.
>
> The code as compiled on Linux is -

>[...]

>
> P.S: No issue with Boost compilation, simply looking for proper
> semantic call for nested std::pair<>.

Have you tried using 'std::make_pair'?

Something like

std::pair<int, std::pair<double,std::string> > spids =
std::make_pair(42, std::make_pair(3.14, std::string("hello")));

...

V
--
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