[Python] _ZSt28__throw_bad_array_new_lengthv trying to import C++ code in Python after...

Run into a frustrating issue trying to import a Python library that itself calls some code I wrote in C++ and compiled into a .so

The C++ code is as follows:

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <cmath>

std::vector<std::string> bigram(std::string initial_str) {
int len = initial_str.size();
std::vector<std::string> tokens;
for (int i = 0; i < len-1; i += 1){
tokens.push_back(initial_str.substr(i, 2));
}
return tokens;
}

std::vector<std::string> vsunion(std::vector<std::string> s1, std::vector<std::string> s2) {
std::vector<std::string> union_str(s1);
union_str.insert(union_str.end(), s2.begin(), s2.end());
std::sort(union_str.begin(), union_str.end());
union_str.erase(std::unique(union_str.begin(), union_str.end()), union_str.end());
return union_str;
}

std::vector<int> ufreq(std::vector<std::string> u, std::vector<std::string> s) {
int len = u.size();
std::vector<int> vfreq;
for (int i = 0; i < len; i += 1){
int freq = std::count(s.begin(), s.end(), u);
vfreq.push_back(freq);
}
return vfreq;
}

float similarity(std::vector<int> f1, std::vector<int> f2) {
float num = std::inner_product(f1.begin(), f1.end(), f2.begin(), 0.0);
float den1 = std::inner_product(f1.begin(), f1.end(), f1.begin(), 0.0);
float den2 = std::inner_product(f2.begin(), f2.end(), f2.begin(), 0.0);
float similarity = num / std::sqrt(den1 * den2);
return similarity;
}

float similarity(std::string string1, std::string string2) {
std::vector<std::string> new_str = bigram(string1);
std::vector<std::string> new_str2 = bigram(string2);
std::vector<std::string> union_str = vsunion(new_str, new_str2);
std::vector<int> freq1 = ufreq(union_str, new_str);
std::vector<int> freq2 = ufreq(union_str, new_str2);
float score = similarity(freq1, freq2);
return score;
}

extern "C" {
float gram(std::string str1, std::string str2)
{
return similarity(str1, str2);
}
}


Which I compiled using:

g++ gram.cpp -shared -o gram.so


and finally I'm trying to import the below script that's throwing the error in the title "_ZSt28__throw_bad_array_new_lengthv could not be located in the dynamic link library":

import ctypes
import sys
import os

dir_path = os.path.dirname(os.path.realpath(__file__))
handle = ctypes.CDLL(dir_path + "/gram.so")

handle.My_Function.argtypes = [ctypes.c_wchar_p]

def gram(string1, string2):
return handle.gram(string1, string2)


Any idea where I might have gone wrong? I can compile a test case instead of the "extern" bit:

int main() {
float score = similarity("John Smith", "Johnny John Smith");
std::cout << score << " ";
std::cin.get();
}


and run as an exe, seemingly without issue; something seems to be going wrong at the

handle = ctypes.CDLL(dir_path + "/gram.so")


stage in the gram library.

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