Problem with Iterator Map C++

Question

the program for a URI exercise hangs (as in infinite loop) when the input (double) is different from an integer or decimal number that is not something with a middle (e.g.: 55.5). I have tried to modify the code in several ways, but apparently the problem is in the second iteration (it2), because without this piece of code it works with any decimal. The strange thing is that with the code the way it is, it hangs exactly after reading the double, at the beginning of the code.

The purpose of the exercise is to pass the amount reported on entry to the smallest possible number of banknotes and coins.

code:

#include <iostream>
#include <map>
#include <iomanip>

using namespace std;

int main(){

double val=0.0;
map<int,int> nota,moeda;
map<int,int>::reverse_iterator it,it2;

cin >> val;

if(val<0.00 || val>1000000.00)
    return 1;

nota[100]=0;
nota[50]=0;
nota[20]=0;
nota[10]=0;
nota[5]=0;
nota[2]=0;

moeda[100]=0;
moeda[50]=0;
moeda[25]=0;
moeda[10]=0;
moeda[5]=0;
moeda[1]=0;

it=nota.rbegin();

while(val>=2){
    while(val-it->first>=0){
        val-=it->first;
        nota[it->first]++;
    }           
    it++;
}   

it2=moeda.rbegin();

while(val>0){
    while(val-it2->first/100.00>=0){
        val-=it2->first/100.00;
        moeda[it2->first]++;
    }           
    it2++;
}

cout << "NOTAS:" << endl;
for(it=nota.rbegin();it!=nota.rend();it++)
    cout << it->second << " nota(s) de R$ " << fixed << setprecision(2) << it->first/1.0 << endl;
cout << "MOEDAS:" << endl;
for(it2=moeda.rbegin();it2!=moeda.rend();it2++)
    cout << it2->second << " moeda(s) de R$ " << fixed << setprecision(2) << it2->first/100.00 << endl;

return 0;
}

Answer 1

You have not implemented a correct stop rule in the two while Ops. Try to include a rule that uses iterator’s, as these are the most important to be tested, since if they are not pointing to a valid position, an undetermined error situation may occur.
Include this test after each iterator increment, for each case:

if (it == nota.rend()) break;

if (it2 == moeda.rend()) break;