How to access the outer most structure test member using map variable mapoftest2? I need to access the structure variable using map object.

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I have below code. I have inserted the data in the structures. I need to access the first value of mapOfTest using mapOfTest2.

C++

#include <iostream>
#include 
using namespace std; 

typedef struct
    {
      string name;
      int id;
    }Test;

typedef struct
    {
      int errCode;
      string errName;
      map<int, test=""> mapOfTest;
    }Test1;

typedef struct
    {
     map < string, Test1> mapOfTest1;
    }Test2;

int main()
{
    map< string, Test2> mapOfTest2;

   return 0;

}

What I have tried:

I have below code. I have inserted the data in the structures. I need to access the first value of mapOfTest using mapOfTest2.

Posted 24-Jan-21 5:04am

Member 15025528

Updated 24-Jan-21 9:46am

CPallini

v2

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2 solutions

Solution 2

Here you are, but...
Are you really sure you want this?

C++

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

struct Test
{
  string name;
  int id;
};

struct Test1
{
  int errCode;
  string errName;
  map<int, Test > mapOfTest;
};

struct Test2
{
  map < string, Test1> mapOfTest1;
};

int main()
{
  Test test[] =
  {
    {"foo", 4},
    {"bar", 2}
  };


  Test1 test1[] =
  {
    5, "error five",
    {
      {5, test[0]} ,
      {25, test[1]}
    },
    6, "error six",
    {
      {6, test[1]} ,
      {36, test[1]}
    }
  };

  Test2 test2 = { {{ "goo", test1[0] }, { "boo", test1[0] }, {"woo", test1[1]}}};

  // access the 'name' field of the 'test[1]' variable ('Test' struct) 
  cout << test2.mapOfTest1["woo"].mapOfTest[6].name << endl;

}

[update]
As per OP request, here it is the code using iterators

C++

auto it1 = test2.mapOfTest1.find("woo");
if ( it1 != test2.mapOfTest1.end() )
{
  auto & mof = it1->second.mapOfTest; // reference to mapOfTest
  auto it = mof.find(6);
  if ( it != mof.end() )
    cout << it->second.name << endl;
}

[/update]

Posted 24-Jan-21 9:46am

CPallini

Updated 24-Jan-21 20:24pm

v2

Comments

Member 15025528 24-Jan-21 22:25pm

Thanks CPallini,
Actually I need this, but using iterator.

CPallini 25-Jan-21 2:25am

I've updated my solution. Now it shows how can you access the data using iterators.

Member 15025528 25-Jan-21 3:01am

Thanks for the help CPallini.
Now I understood the way to access.
Thanks again
Irshad

CPallini 25-Jan-21 3:08am

You are welcome.

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Richard MacCutchan · Accepted Answer · 2021-01-24T05:38:00

Solution 1

The variable mapOfTest2 contains an entry that points to a Test2 object. That in turn has an entry that points to a Test1 object. The Test1 object contains the mapOfTest map. So following the links will get you to that map and give access to its contents. Quite why you have such a complicated set of structures is not clear.

Posted 24-Jan-21 5:38am

Richard MacCutchan

Comments

Member 15025528 24-Jan-21 12:16pm

Thanks for the answer. But I am not getting how to iterate.
Like i have created iterator of mapOfTest2
map< string, Test2>::iterator itr;
for(itr = mapOfTest2.begin(); itr = mapOfTest2.end();itr++)
{

}

then how to access mapOfTest1 and mapOfTest and Test member using mapOfTest2 iterator?

Richard MacCutchan 24-Jan-21 12:21pm

You refer to each item in the map by the iterator, or use one of the map methods to find an entry based on the string field. see map::begin - C++ Reference[^].

Member 15025528 25-Jan-21 3:51am

Thanks for the help Richard.
Irshad