C ++ find_first_not_of

Question

Im a c++ beginner and I'm getting confused with this one, any help would be much appreciated.

#include <iostream>
#include <string>
using namespace std;
int main()
{
    string str;
    cout << "CONVERSION\n\n";
    cout << "Base 11 to Decimal\n";
    cout << "Base 11: ";
    getline(std::cin, str);
    const auto bad_loc = str.find_first_not_of("0123456789aA");
    if (bad_loc != std::string::npos) 
    {
        throw "bad input"; // or whatever handling
    }
    unsigned long ul = std::stoul(str, nullptr, 11);
    cout << "Decimal: " << ul << '\n';
    return 0;
}

The output was

CONVERSION

Base 11 to Decimal
Base 11: 1234AB 

The program stopped and it didn't send me the "bad input". Couldn't find any solution. Thanks in advance

Answer 1

BoBTFish gave the answer in a comment:

Well you don't catch and handle the thrown string. So your program will just exit, and your OS will do whatever it does, which may not include attempting to print the string. For the purposes of this test, it's probably simpler to replace

 throw "bad input"; 

with

 std::cerr << "bad input\\n"; return 1;