newbie question: map<string, int[2]>

[Hyrum Mortensen]

Hi,

If I create a structure like this:
map<string, int[2]> myMap;

How do I access the first element of the array? I get a compiler's
error if I try something like this: myMap["foo"][0]

If the above structure is NOT possible, what is something that's
equivalent?

 

[Rolf Magnus]

Hi,

If I create a structure like this:
map<string, int[2]> myMap;

You can't. Arrays are not assignable, and so they cannot be the element
type of any standard container.

How do I access the first element of the array? I get a compiler's
error if I try something like this: myMap["foo"][0]

If the above structure is NOT possible, what is something that's
equivalent?

struct twoInts
{
int data[2];
}

std::map<std::string, twoInts> myMap;

access it like:

myMap["foo"].data[0];

 

[Victor Bazarov]

If I create a structure like this:
map<string, int[2]> myMap;

You cannot. Arrays cannot be used for values in standard containers.
They do not satisfy the Assignable requirement.

How do I access the first element of the array? I get a compiler's
error if I try something like this: myMap["foo"][0]

Of course.

If the above structure is NOT possible, what is something that's
equivalent?

You need to wrap the array into a class:

struct TwoInts {
int a, b;
int& operator[](int i) {
if (i == 0) return a;
else if (i == 1) return b;
else throw "Out of range";
}
};

then you can use it with a map:

map<string, TwoInts> myMap;

map["foo"][0] = 42;

Victor

 

[Kapil Khosla]

Hi,

If I create a structure like this:
map<string, int[2]> myMap;

How do I access the first element of the array? I get a compiler's
error if I try something like this: myMap["foo"][0]

If the above structure is NOT possible, what is something that's
equivalent?

This code might help.
// This is the main project file for VC++ application project
// generated using an Application Wizard.

#include "stdafx.h"

#using <mscorlib.dll>
#include <map>
#include <string>

using namespace System;

struct twoInts
{
int data[2];
}myStruct;

int main()
{
// Create your data set to be entered into the MAP

myStruct.data[0] = 0;
myStruct.data[1] = 1;

std::map<std::string, twoInts> myMap;
// Insert it into the MAP

myMap["one"] = myStruct;


return 0;
}