How can I read lines in vector<T> like ifstream

Question

In the following code it works correctly:

int main(int argc, char *argv[]) {
    uint64_t bucket_size = (kMemoryAvailable / sizeof(double) - sizeof(std::vector < double > )) * 0.7;

    std::ifstream input_file(input_file_path);
    size_t number_of_buckets = 0;
    while (input_file) {
        WriteBucket(input_file, bucket_size, number_of_buckets);
        ++number_of_buckets;
    }
    std::cout << "number_of_buckets: " << number_of_buckets << std::endl;

    std::vector <std::ifstream> intermediate_outputs;
    for (size_t i = 0; i < number_of_buckets; ++i) {
        intermediate_outputs.push_back(std::ifstream("intermediate_output_" + std::to_string(i)));
    }

    std::ofstream output_file(output_file_path);

    MergeFiles(intermediate_outputs, output_file);
    output_file.close();

    for (size_t i = 0; i < number_of_buckets; ++i) {
        intermediate_outputs[i].close();
        remove(("intermediate_output_" + std::to_string(i)).c_str());
    }
}

I want to execute this code for any type as this code, but the file is not read and entered into the loop

template<typename T>
static void sorting(std::vector<T> &input_file) {
    const uint64_t kMemoryAvailable = 100 * 1024 * 1024;

    uint64_t bucket_size = (kMemoryAvailable / sizeof(double) - sizeof(std::vector<double>)) * 0.7;

    size_t number_of_chunks = 0;
    string output_file_path;

    while (!input_file.empty()) {
        WriteBucket(input_file, bucket_size, number_of_chunks);
        ++number_of_chunks;
    }
    vector<ifstream> intermediate_outputs;
    for (size_t i = 0; i < number_of_chunks; ++i) {
        intermediate_outputs.push_back(ifstream("intermediate_output_" + to_string(i)));
    }

    ofstream output_file(output_file_path);
    MergeFiles(intermediate_outputs, output_file);
    output_file.close();

    for (size_t i = 0; i < number_of_chunks; ++i) {
        intermediate_outputs[i].close();
        remove(("intermediate_output_" + to_string(i)).c_str());
    }

}

In this code I would like to read the input_file from the first code in the WriteBucket method to produce several intermediate_outputs that I will write on later, but this does not work in T .