Sort String

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int string_compare(const void *p1, const void *p2) {
  return strcmp(*(char * const *) p1, *(char * const *) p2);
}
int main(void) {
  const int n = 10;
  char **a = (char **) malloc(n * sizeof(char *));
  for (int i = 0; i < n; i++) {
    a[i] = (char *) malloc(20);
    printf("%d > ", i + 1);
    scanf("%19s", a[i]);
  }
  qsort(a, n, sizeof(char *), string_compare);
  for (int i = 0; i < n; i++)
    printf("%d: %s\n", i + 1, a[i]);
  return 0;
}