Question

While trying to generate a vector of random numbers I stumble across a std::bad_alloc error. Here’s my code:

#include "search.h"
#include "gtest/gtest.h"

int _size = 100;

std::vector<int> GetSortedVector(int size){
    //init vector
    std::vector<int> v(size);
    //fill with random numbers
    for (std::vector<int>::size_type i=0; i < v.size(); i++)
        v.push_back( std::rand()%(2*size) );
    //return the setup vector
    return v;
}

//triggered automatically
TEST(BinarySearch, NonUniqueSorted){
    std::vector<int> v = GetSortedVector(_size);//nothing moves farther than this line
}

P.S.: I do use generate() by now, but am still curious why it failed.

Answer 1

v.push_back increases the size, so i<v.size() is never false.

Since your vector is already size in length, you need to fill it with

for (std::vector<int>::size_type i=0; i < v.size(); i++)
    v[i] = std::rand()%(2*size);

or use reserve instead:

std::vector<int> v;
v.reserve(size);

keep the push_back and check against size. I won’t suggest std::generate because you said you’re already doing it like that.