Thread: maps to structs

Your code only declares the statics, but does not define them.

I'll assume the class definition (the first lump of code) is in a header file, that the definition of ppfromID::init() is in a source file, and the source file #include's the header file somewhere before the definition of ppfromID::init().

To define pp, you need to place the following line in the source file, after #include'ing the header file

Code:

std::map<int,particle_properties> ppfromID::pp;

This is a definition corresponding to the declaration of pp you have shown.

Incidentally, it is not the compiler flagging an undefined reference. It would be the linker.

oh, I've done that. or rather I've done correctly for pp and then when it didn't work and I created the "testmap" I forgot it (adding non-relevant 1 error line to the flaglist that I obviously chose to post here...)

ok, to avoid confusions here is all the relevant code (that I should have given from the start):

Code:

#ifndef PROJECTNAME_TOOLS_H
#define PROJECTNAME_TOOLS_H
#include <map>

struct particle_properties{
/**This struct holds general paticles data (Mass, Charge, etc).		**/
/**It's purpose is to hold data of individual particles	that will 	**/
/**then be called by "ppfromID" (which will hold one				**/
/**particle_properties object for each particle of the SM).			**/
/**Exotic particles added will also be stored here.					**/
public:
	particle_properties(double,int);
	particle_properties(double,int,double);
	double mass;
	int charge;		//(in units of e/3)
	double evaporation_weight;
};

class ppfromID{
public:
	ppfromID(void);
private:
	void init(void);
	static bool initiated;
	static std::map<int,particle_properties> pp;
	static std::map<int,double> testmap;		//TO BE REMOVED!!!
};

Code:

#include "projectname_tools.h"
using namespace std;

particle_properties::particle_properties(double m,int q){
/**CONSTRUCTOR**/
	mass=m;
	charge=q;
	evaporation_weight=0.0;
}

/**static data for ppfromID**/
bool ppfromID::initiated=false;
map<int,particle_properties> ppfromID::pp;
map<int,double> ppfromID::testmap;
/****************************/

ppfromID::ppfromID(void){
/**CONSTRUCTOR**/		
	if (initiated=false){
		init();
		initiated=true;
	}
}

void ppfromID::init(void){
/**Initiates the class (adds the SM particles and their properties)**/	
	pp[1]=particle_properties(.32,1);
	testmap[1]=double(.32);
}

the error message given is error: no matching function for call to ‘particle_properties::particle_properties(). Indicating that the problem is likely how the struct declaration interacting with the map. I tried this...

Code:

	particle_properties temp_pp(.32,1);
	pp[1]=temp_pp;

...with similar results.

any idea what I'm doing wrong?

Code:

pp[1]=temp_pp;

The very act of writing pp[1] attempts to create a particle object using the default constructor which does not exist and hence why you get the error. You need to either create the default constructor or use the map's insert member function to get around this.

pp[1] creates a pair with 1 as the key and a default constructed particle object as the value. Since your default constructor did not exist you got the error. There is no check at this stage that a pair with key 1 exists or not, the pair is simply created as stated in the first sentence. If you wanted to test whether pp[1] existed without actually creating an object with said key, you would need to use the map's find member function. As stated in my earlier post, you can resolve this by either creating a default constructor or using the map's insert member function.

The assignment step of this statement would simply overwrite the default constructed object with a new particle object. This is also what would happen if you attempted to add an "already in use key", the overwrite of an existing value.

The return result of the assignment operation is likely the modified particle object referenced by pp[1], not a pointer to the pair.

I think the best thing to do here is for you to provide the smallest possible compilable example that reproduces the problem.

Originally Posted by killme

for some reason my simpler example works fine.

That's a sign that you are making assumptions about what the problem is. And that those assumptions are incorrect.