utf8rewind字符串处理库

utf8rewind 是跨平台的开源 C 库，扩展默认的字符串处理函数，支持 UTF-8 编码文本。

示例：

 #include "utf8rewind.h"

    int main(int argc, char** argv)
    {
        const char* input = "Hello World!";

        static const size_t output_size = 256;
        char output[output_size];
        wchar_t output_wide[output_size];
        const char* input_seek;
        size_t converted_size;
        int32_t errors;

        memset(output, 0, output_size * sizeof(char));
        memset(output_wide, 0, output_size * sizeof(wchar_t));

        /*            Convert input to uppercase:            "Hello World!" -> "HELLO WORLD!"        */

        converted_size = utf8toupper(
            input, strlen(input),
            output, output_size - 1,
            &errors);
        if (converted_size == 0 ||
            errors != UTF8_ERR_NONE)
        {
            return -1;
        }

        /*            Convert UTF-8 input to wide (UTF-16 or UTF-32) encoded text:            "HELLO WORLD!" -> L"HELLO WORLD!"        */

        converted_size = utf8towide(
            output, strlen(output),
            output_wide, (output_size - 1) * sizeof(wchar_t),
            &errors);
        if (converted_size == 0 ||
            errors != UTF8_ERR_NONE)
        {
            return -1;
        }

        /*            Seek in input:            Hello World!" -> "World!"        */

        input_seek = utf8seek(input, input, 6, SEEK_SET);

        return 0;
    }