c++ - Getting segmentation fault *sometimes* from an attempt at a selection sort implementation -

i've attempted debug on own, can't figure out! i'm getting segmentation faults when running code, when there's not seg fault runs fine , works. guidance appreciated, thanks! also, please keep in mind i'm new c++.

here's have far:

#include <iostream> #include <vector> using namespace std;  vector<int> selection_sort(vector<int> numbers) {     int lowest_number_index;     int lowest_number;     int starting_size = numbers.size();     vector<int> sorted_numbers;     (int = 0; < numbers.size(); ++i) {          // find lowest number         if (numbers[i] <= lowest_number) {             lowest_number_index = i;             lowest_number = numbers[lowest_number_index];         }          // found it! let's add other array         // , remove one.         if (i == numbers.size() - 1 && numbers.size() != 1) {             sorted_numbers.push_back(lowest_number);             numbers.erase(numbers.begin() + lowest_number_index);              // if we're not done sorting             if (sorted_numbers.size() != starting_size) {                 lowest_number_index = 0;                 lowest_number = numbers[lowest_number_index];                 // continue sorting                 = -1;                 continue;             }         } else if (numbers.size() == 1) {             sorted_numbers.push_back(numbers[i]);         }     }      return sorted_numbers; }  int main() {     vector<int> to_sort { 15, 2, 41, 5, 4, 5, 4, 6 };     to_sort = selection_sort(to_sort);      cout << "sorted: ";     (auto = to_sort.begin(); != to_sort.end(); ++it) {         cout << *it << " ";     }     cout << endl; } 

the function has undefined behaviour because there used uninitialized variable lowest_number

int lowest_number;      ^^^^^^^^^^^^^ //... (int = 0; < numbers.size(); ++i) {      // find lowest number     if (numbers[i] <= lowest_number) {         ^^^^^^^^^^^^^^^^^^^^^^^^^^^  

take account variable lowest_number_index uninitialized.

int lowest_number_index;