cat.c

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

int compare(char *name1, char *name2) 
{
  
  char n1[1001], n2[1001];
  int i = 0;

  while (name1[i] != '\0')
  {
    n1[i] = tolower(name1[i]);
    i++;
  }

  n1[i] = '\0';
  i = 0;

  while (name2[i] != '\0')
  {
    n2[i] = tolower(name2[i]);
    i++;
  }

  n2[i] = '\0';

  return strcmp(n1, n2);
}

void sort(char names[][21], int n)
{
  char temp[1001];

  for (int i = 0; i < n - 1; i++) 
    for (int j = 0; j < n - i - 1; j++) 
      if (compare(names[j], names[j + 1]) > 0)
      {
        strcpy(temp, names[j]);
        strcpy(names[j], names[j + 1]);
        strcpy(names[j + 1], temp);
      }
}

int main()
{
  char names[1001][21];
  int n = 0;

  while (scanf("%s", names[n]) != EOF)
    n++;
 
  sort(names, n);
  
  for (int i = 0; i < n; i++)
    puts(names[i]);
  
  return 0;
}