C++ :: How To Qsort Array Of Structs By One Of Its Members

I am versed in qsorting struct members within a struct instance, as in the example below:

Code:
#include <iostream>
#include <stdlib.h>
using namespace std;
struct item_database {

[Code]....

What I CANT do however is to sort an array of structs by one of its members. This is a complete different problem even if it sounds similar.

In other words, the problem is this; Say we have a struct:

Code:
struct item_database {
int key;
string token;
};

Then we declare an array of this struct in the heap:

Code: item_database *idptr = new item_database[700000]; and initialize its values.

How would one go about sorting this heap array of structs by its member function "token"?

I used the following call to qsort (standard library) and call to the compare function but it doesnt work:

Code:
qsort (idptr, 1000, sizeof(string), compare);

Code: int compare (const void* a, const void* b){
if (*(char*)a >= *(char*)b)
return 1;
else
return -1;
}

Or in more lamens terms say we have the following stuct instances:
Key: Token:
1 Hello
2 World
3 How
4 Are
5 You

Then I need those structs to order according to token (alphabetically, increasing or decreasing depending whats in our compare function).....