Question

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Why does calling boost:split() give so many warnings?

So, this is my code:

Account ParseString(string data){
    vector <string> fields;
    boost::split( fields, data, boost::is_any_of( "a,;" ));
    int limit = fields.size();
    for(int i = 0; i < limit; i++)
        cout << fields[i] << endl;
}

and this is what I get when trying to compile:

d:\program files (x86)\visualstudio\vc\include\xutility(2227): warning C4996: 'std::_Copy_impl': Function call with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators'

My question is, what have I done wrong? What can I do to prevent those error messages?

Answer 1

You haven’t done anything wrong. Visual Studio is being overly cautious. In debug mode, visual studio uses something called “Checked Iterators”. Pointers are also iterators, but the checking mechanism doesn’t work with them. So when a standard library algorithm is called with pointers, which is something that boost::split does, it issues this warning.

You’ll get the same warning with this obviously safe code:

int main()
{
    int x[10] = {};
    int y[10] = {};
    int *a = x, *b = y;
    std::copy(a, a+10, b);
}

Disable the warning. It’s for beginners. It’s on by default for the safety of beginners, because if it was off by default, they wouldn’t know how to turn it on.