Why does my try catch exception stop working after the catch? - c++

Question

I have a segment of code here that runs partially. I am able to input both the characters (c, a, r) and numbers initially, but after entering a character input, the code no long accepts integer inputs. Why does this happen?
I think it has something to do with my try catch exception.
code:
#include <iostream>
#include <vector>
#include <string>
#include <iomanip>
using namespace std;
int item;
string input;
float total = 0;
int flag = 0;
float maintotal = 0;
int main() {
cout.precision(2);
cout << std::fixed;
cout << "Vending Machine" << endl;
cout << "----Items------" << endl;
vendingMachine();
cout << "Enter c to checkout" << endl;
cout << "Enter a to add items" << endl;
cout << "Enter r to remove items" << endl;
while (true) {
cout << "Enter your selection: " << flush;
cin >> input;
try
{
item = stoi(input); //convert to int
}
catch (exception &e)
{
//std::cout << e.what();
flag = -1; //if not set flag
if (input == "c"){
checkout();
}
if (input == "a") {
add();
cout << "mainadd total: " << total << endl;
}
if (input == "r") {
remove();
}
}
if (flag != -1) //only execute with no errors
{
total = enterSelection();
cout << "total from main: " << total << endl;
}
}
return 0;
}

Answer 1

Once you've set flag to -1, it's never changed back to 0. The initialization you perform at the top of the file happens just once, before main is even called. So, after that, when you set it to -1 in the catch block, it never went to a part of the code that set it back to 0. As you saw, setting flag = 0 at the beginning of the while loop corrects that omission.