c程序实现unicode字符转utf-8字符

下面是一个unicode字符转换为utf-8的c程序实现：

/*
* =====================================================================================
*
* Filename: unicodetoutf8.c
*
* Description:
*
* Version: 1.0
* Created: 08/06/2015 10:53:31 AM
* Revision: none
* Compiler: gcc
*
* Author: YOUR NAME (),
* Organization:
*
* =====================================================================================
*/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int unicode_to_utf8 (unsigned int codepoint, char *str)
{
　　char out[];
　　if (codepoint < 0x80)
　　{
　　　　out[] = (char)codepoint;
　　　　strncpy (str, out, );
　　}
　　else if (codepoint < 0x800)
　　{
　　　　out[] = 0xC0 | (codepoint >> );
　　　　out[] = 0x80 | (codepoint & 0x0000003F);
　　　　strncpy (str, out, );
　　}
　　else if (codepoint < 0x10000)
　　{
　　　　out[] = 0xE0 | (codepoint >> );
　　　　out[] = 0x80 | ((codepoint & 0x00000FFF) >> );
　　　　out[] = 0x80 | (codepoint & 0x0000003F);
　　　　strncpy (str, out, );
　　}
　　else
　　{
　　　　out[] = 0xF0 | (codepoint >> );
　　　　out[] = 0x80 | ((codepoint & 0x0003FFFF) >> );
　　　　out[] = 0x80 | ((codepoint & 0x00000FFF) >> );
　　　　out[] = 0x80 | (codepoint & 0x0000003F);
　　　　strncpy (str, out, );
　　}

　　return ;
}

/*
* === FUNCTION ======================================================================
* Name: main
* Description:
* =====================================================================================
*/
int main ( int argc, char *argv[] )
{
　　//unsigned int codepoint = 0x6c41;
　　unsigned int codepoint = 0xFFFF;
　　char str[] = {};
　　unicode_to_utf8 (codepoint, str);
　　printf ("str:%s\n", str);
　　return EXIT_SUCCESS;
}     /* ---------- end of function main ---------- */