sort_str.c

/* Listing 11.29: sort_str.c -- reads in and sorts strings */
#include <stdio.h>
#include <string.h>
#define SIZE 81                      /* string length limit, including \0  */
#define LIM 20                       /* maximum number of lines to be read */
#define HALT ""                      /* null string to stop input          */
void stsrt(char *strings[], int num);/* string-sort function               */
char * s_gets(char * st, int n);

int main(void)
{
   char input[LIM][SIZE];            /* array to store input               */
   char *ptstr[LIM];                 /* array of pointer variables         */
   int ct = 0;                       /* input count                        */
   int k;                            /* output count                       */
   
   printf("Input up to %d lines, and I will sort them.\n",LIM);
   printf("To stop, press the Enter key at a line's start.\n");
   
   while(ct < LIM && s_gets(input[ct], SIZE) != NULL
	&& input[ct][0] != '\0')
   {
      ptstr[ct] = input[ct];   /* set ptrs to strings                      */
      ct++;
   } 
   stsrt(ptstr, ct);           /* string sorter                            */
   puts("\nHere's the sorted list:\n");
   for(k=0; k < ct; k++)
      puts(ptstr[k]);         /* sorted pointers                           */
   
   return 0;
}

/* string-pointer-sorting function */
void stsrt(char *strings[], int num)
{
   char *temp;
   int top, seek;
   
   for(top = 0; top < num-1; top++)
      for(seek = top + 1; seek < num; seek++)
         if(strcmp(strings[top],strings[seek]) > 0)
         {
            temp = strings[top];
            strings[top] = strings[seek];
            strings[seek] = temp;
         }
}

char * s_gets(char * st, int n)
{
   char * ret_val;
   int i = 0;
   
   ret_val = fgets(st, n, stdin);
   if(ret_val)
   {
      while(st[i] != '\n' && st[i] != '\0')
         i++;
      if(st[i] == '\n')
         st[i] = '\0';
      else // must have words[i] == '\0'
         while(getchar() != '\n')
            continue;
   }
   return ret_val;
}