Function returning NaN in C++ - c++

Question

I'm creating a software in C++ loops on one function(double) indefinitely. After going through the loop the first time, the second time it runs, it returns 'nan'. Where did I go wrong.
int main()
{
double Balance = 100;
for (int i = 0; i < 5; i++) {
nyaradzo(Balance, i);
}
}
double nyaradzo(double bal, int pass)
{
int x = bal;
double Amount;
string policy_number;
double confirmation;
cout<<"WELCOME TO NYARADZO ONLINE POLICY PAYMENT"<<endl;
cout<<"ENTER YOUR POLICY NUMBER"<<endl;
cin>>policy_number;
cout<<"ENTER AMOUNT YOU WISH TO PAY FOR YOU POLICY"<<endl;
cin>>Amount;
cout<<"YOUR POLICY NUMBER IS: "<<policy_number<<endl;
cout<<"YOU HAVE CHOSEN TO PAY $"<<Amount<<" FOR YOUR FUNERAL POLICY. \n Is this information correct?"<<endl;
cout<<"1 TO CONFIRM"<<endl;
cout<<"2 TO CANCEL"<<endl;
cin>>confirmation;
if (confirmation==1) {
if (Amount <= x) {
x -= Amount;
cout<<"Transaction Complete"<<endl;
cout<<"YOUR BALANCE IS $"<<x<<endl;
return x;
}
else if (Amount > x) {
cout<<"TRANSACTION DENIED \a"<<endl;
cout<<"You cannot withdraw more than your actual balance..."<<endl;
return 0;
}
else {
cout <<x << endl;
cout<<"TRANSACTION DENIED \a"<<endl;
cout<<"Your purchase must be greater than or at least equal to $1"<<endl;
return 0;
}
}
else if (confirmation==2) {
cout<<"YOU HAVE CHOSEN TO CANCEL YOUR ZESA TRANSACTION"<<endl;
// transaction(bal, pass);
}
else
{
cout << "Invalid selection" << endl;
return 0;
}
}
When it goes through the loop a second time, it fails.

Answer 1

Not all paths in nyaradzo return a value. You should enable all your compiler warnings. It should alert you of this. Since x = bal and you only modify x when the amout is ok, add this as the final line of the func:
return x;
And change type of x to double. Or get rid of x and use bal throughout.
Also, I assume you want to keep a running balance. Then you should change the for loop to:
for (int i = 0; i < 5; i++) {
Balance = nyaradzo(Balance, i);
}