C言語で、UTF-8 の文字列から Unicode のコードポイントを取得するやりかた ref: http://qiita.com/ynakajima/items/0510115ba19ab66e6670

file1.c

// UCS4に変換
gunichar* codepoints = g_utf8_to_ucs4_fast(utf8_text, -1, NULL); 

file2.txt

$ brew install glib

file3.txt

$ gcc -Wall -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include -lglib-2.0 -o utf8_to_codepoint utf8_to_codepoint.c

file4.txt

$ ./utf8_to_codepoint "UTF-8の文字列を変換"
[U+0055] [U+0054] [U+0046] [U+002D] [U+0038] [U+306E] [U+6587] [U+5B57] [U+5217] [U+3092] [U+5909] [U+63DB] 

file5.txt

$ ./utf8_to_codepoint "𠀋𡈽𡌛𡑮"
[U+2000B] [U+2123D] [U+2131B] [U+2146E] 

file6.c

#include <glib.h>

gunichar* g_utf8_to_ucs4_fast(const gchar *str,
                              glong len,
                              glong *items_written);

utf8_to_codepoint.c

#include <stdio.h>
#include <glib.h>

int main (int argc, char* argv[]) {

  // 引き数が渡されてなかったら終了
  if (argc < 2) {
    fprintf(stderr, "usage: %s text\n", argv[0]);
    return 1;
  }

  // 引き数として渡された文字列を代入
  char* utf8_text = argv[1];

  // テキストの文字数を取得
  glong length = g_utf8_strlen(utf8_text, -1);

  // UCS4に変換
  gunichar* codepoints = g_utf8_to_ucs4_fast(utf8_text, -1, NULL); 

  // 1文字づつ code point を出力
  for (int i = 0; i < length; i++) {
    printf("[U+%04X] ", codepoints[i]);
  }
  printf("\n");

  // 終了処理
  g_free(codepoints);
  return 0;
}