CODEWITHSUNDEEP
c++unicodecout
Lerp
Lerp

Reputation: 3127

Output arbitrary number as unicode

How can I make an arbitrary number be interpreted as Unicode when outputted to the terminal?

So for example:

#include <iostream>

int main() {
    int euro_dec = 0x20AC;

    std::cout << "from int: " << euro_dec
              << "\nfrom \\u: \u20AC" << std::endl;

    return 0;
}

This prints:

from int: 8364
from \u: €

What does the escape sequence \u do to make the number 0x20AC be interpreted as Unicode?

I tested using wcout and the output was:

from int: 8364
from \u:

Upvotes: 4

Views: 104

Answers (2)

ecatmur
ecatmur

Reputation: 157414

A unicode escape sequence occurring in program text is converted to the equivalent Unicode character at the very first phase of translation (2.2p1b1 [lex.phases]). This occurs even before the program is tokenized or preprocessed.

To convert a Unicode codepoint expressed as an integer to your native narrow multibyte encoding, use c32rtomb:

#include <cuchar>

char buf[MB_CUR_MAX];
std::mbstate_t ps{};
std::size_t ret = std::c32rtomb(buf, euro_dec, &ps);
if (ret != static_cast<std::size_t>(-1)) {
    std::cout << std::string(buf, &buf[ret]);   // outputs €
}

Note that cuchar is poorly supported; if you know that your native narrow string encoding is UTF-8 you can use codecvt_utf8<char32_t> but otherwise you'll have to use platform-specific facilities.

Upvotes: 3

Some programmer dude
Some programmer dude

Reputation: 409356

When you output the integer variable, the library converts the value to text, it doesn't actually output the value as an integer.

When using the "\u", it's the compiler which reads the number and converts it to the appropriate byte sequence which it inserts directly into the literal string.

Upvotes: 0

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