How to convert a Unicode code point to characters in C++ using ICU?

Somehow I couldn't find the answer in Google. Probably I'm using the wrong terminology when I'm searching. I'm trying to perform a simple task, convert a number that represents a character to the characters itself like in this table: http://unicode-table.com/en/#0460

For example, if my number is 47 (which is '\'), I can just put 47 in a char and print it using cout and I will see in the console a backslash (there is no problem for numbers lower than 256).

But if my number is 1120, the character should be 'Ѡ' (omega in Latin). I assume it is represented by several characters (which cout would know to convert to 'Ѡ' when it prints to the screen).

How do I get these "several characters" that represent 'Ѡ'?

I have a library called ICU, and I'm using UTF-8.

Solution

What you call Unicode number is typically called a code point. If you want to work with C++ and Unicode strings, ICU offers a icu::UnicodeString class. You can find the documentation here.

To create a UnicodeString holding a single character, you can use the constructor that takes a code point in a UChar32:

icu::UnicodeString::UnicodeString(UChar32 ch)

Then you can call the toUTF8String method to convert the string to UTF-8.

Example program:

#include <iostream>
#include <string>

#include <unicode/unistr.h>

int main() {
    icu::UnicodeString uni_str((UChar32)1120);
    std::string str;
    uni_str.toUTF8String(str);
    std::cout << str << std::endl;

    return 0;
}

On a Linux system like Debian, you can compile this program with:

g++ so.cc -o so -licuuc

If your terminal supports UTF-8, this will print an omega character.