Question

I’m working with a C++ library, and need to create an unsigned char from a UTF-8 code point. For example, if the code point is decimal 610 (a ‘latin letter small capital G’), how would I create this in C++?

I javascript, I can do the following:

var temp = String.fromCharCode(610);
console.log(temp); // Outputs a small 'G' (correct)
var codePoint = temp.charCodeAt(0);
console.log(codePoint); // Outputs 610 (correct)

In C++ have tried:

unsigned char temp = (unsigned char)610;
// compiles, but
Debug::WriteLine((int)temp); // outputs 98 (??)

Please provide a code example in C++ which performs the same as the javascript example above.

The environment is in managed C++, but I want to avoid using CLR types as I’m interfacing with a 3rd party library.

Answer 1

An unsigned char is to small to hold a value of 610 (assuming a char is 8 bits wide, it can only hold values from 0 to 255), so it will wrap around*

Use char16_t to store a 16-bit char (or char32_t for a 32-bit char, which UTF-8 requires).

char32_t temp = (char32_t)610;
Debug::WriteLine(temp); // outputs 610 (!!)

If you want to handle UTF-8 strings, use UTF-8 string literals:

u8"I'm a UTF-8 string."

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*It will wrap around even twice in your example:

610 – 256 – 256 = 98