perpendicular and "up tack" code points

#include <stdio.h>
#include <stdbool.h>

#include <ft2build.h>
#include FT_FREETYPE_H

FT_Library library;
FT_Face face;
FT_Error error;

int main(void) {

  FT_Init_FreeType(&library);
  FT_New_Face(library, "KaTeX_Main-Regular.ttf", 0, &face);

  int code_point;
  FT_UInt index;

  code_point = 0x22a5;  // up tack
  index = FT_Get_Char_Index(face, code_point);
  printf("%x: %u\n", code_point, index);

  code_point = 0x27c2;  // perpendicular
  index = FT_Get_Char_Index(face, code_point);
  printf("%x: %u\n", code_point, index);
}

output:

22a5: 247
27c2: 0

The glyph index. 0 means ‘undefined character code’.