Exercise5-15.c

/*Exercise 5-15. Add the option -f to fold upper and lower case together, so that
case distinctions are not made during sorting; for example, a and A compare equal.*/

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

#define MAXLINES 5000       /* max #lines to be sorted */
char *lineptr[MAXLINES];    /* pointers to text lines */

int readlines(char *lineptr[], int nlines);
void writelines(char *lineptr[], int nlines);

void my_qsort(void *lineptr[], int left, int right, int (*comp)(void *, void *), int reverse, int fold);
int numcmp(char *, char *);

/* sort input lines */
int main(int argc, char *argv[])
{
  int nlines;     /* number of input lines read */
  int numeric = 0;/* if numeric sort */
  int reverse = 0;/*reveser order*/
  int fold = 0;   /*old upper lower case*/

  while (--argc>0&& **(++argv)=='-')
  {
      if( *(*(argv)+1)=='n')
          numeric=1;
      else if ( *(*(argv)+1)=='r')
          reverse=1;
      else if ( *(*(argv)+1)=='f')
          fold=1;
  }

  if ((nlines = readlines(lineptr, MAXLINES)) >= 0)
  {
      my_qsort((void**) lineptr, 0, nlines-1, (int (*)(void*,void*))(numeric ? numcmp : strcmp), reverse ? 1:0, fold ? 1:0);
      writelines(lineptr, nlines);
      return 0;
  }
  else
  {
      printf("input too big to sort\n");
      return 1;
  }
}

#define MAXLEN 1000 /* max length of any input line */
size_t get_line(char *, int);
char *alloc(int);

/* readlines: read input lines */
int readlines(char *lineptr[], int maxlines)
{
  int len, nlines;
  char *p, line[MAXLEN];

  nlines = 0;
  while ((len = get_line(line, MAXLEN)) > 0)
      if (nlines >= maxlines || (p = alloc(len))== NULL)
          return -1;
      else
      {
          line[len-1] = '\0'; /* delete newline */
          strcpy(p, line);
          lineptr[nlines++] = p;
      }

  return nlines;
}

/* writelines: write output lines */
void writelines(char *lineptr[], int nlines)
{
  int i;
  for (i = 0; i < nlines; i++)
      printf("%s\n", lineptr[i]);
}

/* qsort: sort v[left]...v[right] into increasing order */
void my_qsort(void *v[], int left, int right, int (*comp)(void *, void *), int reverse, int fold)
{
  int i, last;
  void swap(void *v[], int, int);
  if (left >= right)              /* do nothing if array contains */
      return;                     /* fewer than two elements */
  swap(v, left, (left + right)/2);
  last = left;
  for (i = left+1; i <= right; i++)
      if(reverse)
      {
          if (fold)
          {
              char a,b;

              if (isalpha(*(char*)v[i]) && isalpha(*(char*)v[left]))
              {
                  a=tolower(*(char*)v[i]);
                  b=tolower(*(char*)v[left]);
                  if ((*comp)(&a, &b) > 0)
                      swap(v, ++last, i);
              }else if (isalpha(*(char*)v[i]))
              {
                  a=tolower(*(char*)v[i]);
                  if ((*comp)(&a, v[left]) > 0)
                      swap(v, ++last, i);

              }else if (isalpha(*(char*)v[left]))
              {
                  b=tolower(*(char*)v[left]);
                  if ((*comp)(v[i], &b) > 0)
                      swap(v, ++last, i);
              }
              else
              {
                  if ((*comp)(v[i], v[left]) > 0)
                      swap(v, ++last, i);
              }
          }
          else
          {
              if ((*comp)(v[i], v[left]) > 0)
                  swap(v, ++last, i);
          }
      }
      else
      {
          if (fold)
          {
              char a,b;

              if (isalpha(*(char*)v[i]) && isalpha(*(char*)v[left]))
              {
                  a=tolower(*(char*)v[i]);
                  b=tolower(*(char*)v[left]);
                  if ((*comp)(&a, &b) < 0)
                      swap(v, ++last, i);
              }else if (isalpha(*(char*)v[i]))
              {
                  a=tolower(*(char*)v[i]);
                  if ((*comp)(&a, v[left]) < 0)
                      swap(v, ++last, i);

              }else if (isalpha(*(char*)v[left]))
              {
                  b=tolower(*(char*)v[left]);
                  if ((*comp)(v[i], &b) < 0)
                      swap(v, ++last, i);
              }
              else
              {
                  if ((*comp)(v[i], v[left]) < 0)
                      swap(v, ++last, i);
              }
          }
          else
          {
              if ((*comp)(v[i], v[left]) < 0)
                  swap(v, ++last, i);
          }
      }

  swap(v, left, last);
  my_qsort(v, left, last-1, comp, reverse, fold);
  my_qsort(v, last+1, right, comp, reverse, fold);
}

/* numcmp: compare s1 and s2 numerically */
int numcmp(char *s1, char *s2)
{
  double v1, v2;
  v1 = atof(s1);
  v2 = atof(s2);
  if (v1 < v2)
      return -1;
  else if (v1 > v2)
      return 1;
  else
      return 0;
}

void swap(void *v[],int i, int j)
{
  void *temp;

  temp = v[i];
  v[i] = v[j];
  v[j] = temp;
}

#define ALLOCSIZE 10000
static char allocbuf[ALLOCSIZE];
static char *allocp = allocbuf;

char *alloc(int n)
{
  if(ALLOCSIZE + allocbuf - allocp>= n )
  {
      allocp += n;
      return allocp - n;
  }
  else
      return 0;
}

size_t get_line(char* f_line,int n)
{
  int c;
  size_t size=(size_t)f_line;

  while(((size_t)f_line-size)<n && (c=getchar())!=EOF && c!='\n')
      *f_line++=c;

  if(c=='\n')
      *(f_line++)=c;

  *(f_line)='\0';

  return (size_t)f_line-size;
}