Language: C

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

struct GuideData {
	int index;
	char S[11];
	int  point;
};

int GuidSort(const void *a, const void *b) {
  int a_cmp, b_cmp;
  GuideData *A, *B;
  A =  (GuideData *)a;
  B =  (GuideData *)b;
  a_cmp = strcmp(A->S, B->S);
  if (a_cmp != 0) {
	  return a_cmp;
  }
  b_cmp = B->point - A->point;
  return  b_cmp;
}

int main(void)
{
     GuideData *data;
	 int N, i;

	 scanf("%d", &N);

	 data = (GuideData *)malloc(sizeof(GuideData)*N);

	 for (i = 0; i < N; i++) {
		 scanf("%s %d", data[i].S, &(data[i].point));
		 data[i].index = i + 1;
	 }

    qsort(data, N, sizeof(GuideData),  GuidSort);

	 for (i = 0; i < N; i++) {
		 printf("%d\n", data[i].index);
	 }
	free(data);

	return 0;

}


Compiler output:
main.c: In function 'GuidSort':
main.c:13:3: error: unknown type name 'GuideData'; use 'struct' keyword to refer to the type
   13 |   GuideData *A, *B;
      |   ^~~~~~~~~
      |   struct 
main.c:14:9: error: 'GuideData' undeclared (first use in this function)
   14 |   A =  (GuideData *)a;
      |         ^~~~~~~~~
main.c:14:9: note: each undeclared identifier is reported only once for each function it appears in
main.c:14:20: error: expected expression before ')' token
   14 |   A =  (GuideData *)a;
      |                    ^
main.c:15:20: error: expected expression before ')' token
   15 |   B =  (GuideData *)b;
      |                    ^
main.c:16:19: error: request for member 'S' in something not a structure or union
   16 |   a_cmp = strcmp(A->S, B->S);
      |                   ^~
main.c:16:25: error: request for member 'S' in something not a structure or union
   16 |   a_cmp = strcmp(A->S, B->S);
      |                         ^~
main.c:20:12: error: request for member 'point' in something not a structure or union
   20 |   b_cmp = B->point - A->point;
      |            ^~
main.c:20:23: error: request for member 'point' in something not a structure or union
   20 |   b_cmp = B->point - A->point;
      |                       ^~
main.c: In function 'main':
main.c:26:6: error: unknown type name 'GuideData'; use 'struct' keyword to refer to the type
   26 |      GuideData *data;
      |      ^~~~~~~~~
      |      struct 
main.c:31:18: error: 'GuideData' undeclared (first use in this function)
   31 |          data = (GuideData *)malloc(sizeof(GuideData)*N);
      |                  ^~~~~~~~~
main.c:31:29: error: expected expression before ')' token
   31 |          data = (GuideData *)malloc(sizeof(GuideData)*N);
      |                             ^
main.c:34:40: error: request for member 'S' in something not a structure or union
   34 |                  scanf("%s %d", data[i].S, &(data[i].point));
      |                                        ^
main.c:34:53: error: request for member 'point' in something not a structure or union
   34 |                  scanf("%s %d", data[i].S, &(data[i].point));
      |                                                     ^
main.c:35:25: error: request for member 'index' in something not a structure or union
   35 |                  data[i].index = i + 1;
      |                         ^
main.c:41:40: error: request for member 'index' in something not a structure or union
   41 |                  printf("%d\n", data[i].index);
      |                                        ^