Initializing the basic string of uint16_t

Question

I have a const basic string in my class:

class foo {
   const basic_string<uint16_t> baz;
};

How do I initialize it?

The main goals I want to achieve are those:

• no overhead in creation
• readable for the user so for instance convert from "Potato" rather than from some buffer with numbers (if it is doable)
• cross platform code
• wont generate compiler warning... company policy

I am using c++11.

Answer 1

How do I initialize it?

Using any of the basic_string constructors. In your example you have used the default constructor. Here is an example of using the initializer list:

const basic_string<uint16_t> baz {
   uint16_t(u't'),
   uint16_t(u'e'),
   uint16_t(u's'),
   uint16_t(u't'),
};

---

I suspect that it would be much easier for you to use std::u16string instead:

const std::u16string baz = u"test";

The characters can then later be converted to uint16_t (from char16_t ) when you need that:

uint16_t c = baz[0];

Answer 2

You can combine UTF-16 literals ( u prefix) with user-defined suffixes:

std::basic_string<uint16_t> operator "" _u16(char16_t const *begin, std::size_t len)
{
    std::basic_string<uint16_t> str;

    if (begin != nullptr && len != 0) {
        char16_t const *end = begin + len;

        str.reserve(len);

        std::copy(begin, end, std::back_inserter(str));
    }

    return str;
}

Now you can initialize your strings like so:

std::basic_string<uint16_t> str{u"testing"_u16};

There is no more overhead with this approach than there is creating a "standard" std::string from a string literal, as in either approach the string must be copied into a new heap allocation.