Thread: STL map

This is a sample code i have, can anyone guide me how do i solve this problem, i have read alot of maps, but i need help on how to get it right.

Code:

// There is Apple class
//Fruit.h

std::map<std::string,Apple> apples;

// I have this method in, Fruit.cpp

//Fruit.cpp   
//have to use insert() method of map

void Fruit::addApple(const Apple& a){
		
           apples.insert(std::pair<string, Apple>);


// error: expected primary-expression before ')' token 

//create apple and use 'other' addApple method

void Fruit::addApple(const string id, const int duration){
		
		       Apple(id, duration); 
		       addApple(Apple);

// error: expected primary-expression before ')' token

how do i pass a reference to a object:

void Fruit::addApple(const Apple& a){
apples.insert(string, &a); //error: expected primary-expression before ',' token

You are using a string as the key to the map. What does that string represent? Is that an id?