CODEWITHSUNDEEP
c++pointersvectorreference
Arrrow
Arrrow

Reputation: 542

pass vector by reference or by pointer

I have the following function: 

void write_to_File(std::vector<uint16_t> *vector) {
    std::fstream file;
    file.open(writePath, std::fstream::out | std::fstream::binary);
    if (file.is_open()) {
         file.write(reinterpret_cast<char*>(&(*vector)[0]), vector->size()*sizeof(uint16_t));
    } else {
        std::cout << "file not found!";
        return;
    }
    file.close();
}

This method doesn't actually change vector, but since it is getting casted I can't make it a const reference. If I use just a reference then cpplint will complain it has to be either const or a pointer.

warning: Is this a non-const reference? If so, make const or use a pointer: std::vector &vector [runtime/references] [2]

Should I just ignore cpplint and make it a reference, keep this code (with the pointer) or make it a const reference and cast a copy?

Upvotes: 2

Views: 1352

Answers (1)

Martin Bonner supports Monica
Martin Bonner supports Monica

Reputation: 28987

As noted in the comments, the correct answer in your case is:

void write_to_File(const std::vector<uint16_t>& vector) {
    std::fstream file;
    file.open(writePath, std::fstream::out | std::fstream::binary);
    if (file.is_open()) {
         const auto ptr = reinterpret_cast<const char*>(&vector[0]);
         file.write(ptr, vector.size()*sizeof(uint16_t));
    } else {
        std::cout << "file not found!";
        return;
    }
    file.close();
}

However, I think the cpplint error is wrong (this is a matter of opinion of course). I use the rule "if nullptr is a valid value, use a pointer, otherwise use a reference".

Upvotes: 1

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