From 6f9e88bee99e0fae4d7ec67022979501c7fa2b01 Mon Sep 17 00:00:00 2001
From: sinanmohd <pcmsinan@gmail.com>
Date: Thu, 30 Jun 2022 22:46:08 +0530
Subject: 5.17

---
 5.17.c | 259 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 259 insertions(+)
 create mode 100644 5.17.c

diff --git a/5.17.c b/5.17.c
new file mode 100644
index 0000000..3469a4e
--- /dev/null
+++ b/5.17.c
@@ -0,0 +1,259 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+#define MAXLINES 5000
+
+char *lineptr[MAXLINES];
+
+int realines(char *lineptr[], int max);
+void writelines(char *lineptr[], int nlins);
+void my_qsort(char *lineptr[], int left, int right, int (*cmp)(const char *, const char *));
+int numcmp(const char to[], const char from[]);
+int strcmp_ignore_case(const char str1[], const char str2[]);
+int reverse(const char str1[], const char str2[]);
+int mystcmp(const char to[], const char from[]);
+int (*compare)(const char str1[], const char str2[]);
+int (*strcmp_base)(const char to[], const char from[]);
+int isdirectory(char input);
+int field_skip(const char str[]);
+
+int directory_order_bool, field_bool;
+
+
+int 
+main(int argc, char *argv[])
+{
+  char flag;
+  int numeric = 0, reverse_bool = 0, ignore_case_bool = 0;
+  int nlins;
+
+  while (--argc > 0 && **++argv == '-')
+    while ((flag = *++*argv))
+      switch (flag) {
+        case 'n' :
+          numeric = 1;
+          break;
+        case 'r' :
+          reverse_bool = 1;
+          break;
+        case 'f' :
+          ignore_case_bool = 1;
+          break;
+        case 'd' :
+          directory_order_bool = 1;
+          break;
+        case 'l' :
+          while (isdigit(*++*argv))
+            field_bool = field_bool * 10 + **argv - '0';
+
+          (*argv)--;
+          break;
+        default :
+          printf("Err: illigial option %c\n", flag);
+      }
+
+  if (argc)
+    printf("Usage: sort -nrf\n");
+  else if ((nlins = realines(lineptr, MAXLINES)) > 0) {
+
+    strcmp_base = ignore_case_bool ? strcmp_ignore_case : mystcmp;
+    compare = numeric ? numcmp : strcmp_base;
+
+    my_qsort(lineptr, 0, nlins - 1, reverse_bool ? reverse : compare);
+    writelines(lineptr, nlins);
+  }
+
+  return 0;
+}
+
+void swap(char *lineptr[], int to, int from);
+
+void 
+my_qsort(char *lineptr[], int left, int right, int (*cmp)(const char *, const char *))
+{
+  int last, i;
+
+  if (left >= right)
+    return;
+
+  swap(lineptr, left, (left+right)/2);
+  last = left;
+
+  for (i = left+1; i <= right; i++) {
+    if ((*cmp)(lineptr[i], lineptr[left]) < 0)
+      swap(lineptr, ++last, i);
+
+  }
+  swap(lineptr, left, last);
+
+  my_qsort(lineptr, left, last-1, cmp);
+  my_qsort(lineptr, last+1, right, cmp);
+}
+
+int 
+numcmp(const char to[], const char from[])
+{
+  if (field_bool) {
+    to += field_skip(to);
+    from += field_skip(from);
+  }
+
+  double n1 = atof(to);
+  double n2 = atof(from);
+
+  if (n1 < n2)
+    return -1;
+  else if (n1 > n2)
+    return 1;
+  else 
+    return 0;
+}
+
+void 
+swap(char *lineptr[], int to, int from)
+{
+  char *temp;
+
+  temp = lineptr[to];
+  lineptr[to] = lineptr[from];
+  lineptr[from] = temp;
+}
+
+void 
+writelines(char *lineptr[], int nlins)
+{
+  while (nlins--)
+    printf("%s", *lineptr++);
+}
+
+#define MAXLEN 1000
+int sneed_getine(char str[], int max);
+
+int 
+realines(char *lineptr[], int max)
+{
+  int len, nlins;
+  char buff[MAXLEN], *temp;
+
+  for (nlins = 0; (len = sneed_getine(buff, MAXLEN)) > 0; nlins++) {
+    if (nlins < max && (temp = malloc(len+1)) != NULL) {
+      strcpy(temp, buff);
+      lineptr[nlins] = temp;
+    }
+
+    else 
+      return -1;
+  }
+
+  return nlins;
+}
+
+int 
+sneed_getine(char str[], int max)
+{
+  char input;
+  char *str_og = str;
+
+  while ( --max && (input = getchar()) != EOF && input != '\n')
+    *str++ = input;
+
+  if (max && input == '\n')
+    *str++ = input;
+
+  *str = '\0';
+
+  return str - str_og;
+}
+
+int 
+reverse(const char str1[], const char str2[])
+{
+  return (*compare)(str2, str1);
+}
+
+int 
+strcmp_ignore_case(const char to[], const char from[])
+{
+  if (field_bool) {
+    to += field_skip(to);
+    from += field_skip(from);
+  }
+
+  if (directory_order_bool) {
+    for (; *to && *from; to++, from++)
+      if ((isdirectory(tolower(*from)) && tolower(*from) != tolower(*to)) || (field_bool && (isblank(*from) || isblank(*to))))
+        break;
+  }
+
+  else
+    for (; *to && *from && tolower(*to) == tolower(*from); to++, from++)
+      if (field_bool && (isblank(*from) || isblank(*to)))
+        break;
+
+  return tolower(*to) - tolower(*from);
+}
+
+int 
+isdirectory(char input)
+{
+  if (isalpha(input) || isdigit(input) || isblank(input))
+    return 1;
+  else 
+    return 0;
+}
+
+int 
+mystcmp(const char to[], const char from[])
+{
+  if (field_bool) {
+    to += field_skip(to);
+    from += field_skip(from);
+  }
+
+  if (directory_order_bool) {
+    for (; *to && *from; to++, from++)
+      if ((isdirectory(*from) && *from != *to) || (field_bool && (isblank(*from) || isblank(*to))))
+        break;
+  }
+
+  else
+    for (; *to && *from && *to == *from; to++, from++)
+      if (field_bool && (isblank(*from) || isblank(*to)))
+        break;
+
+  return *to - *from;
+}
+
+int 
+field_skip(const char str[])
+{
+  int count, inside;
+  const char *str_og;
+
+  str_og = str;
+
+  while (isblank(*str))
+     str++;
+
+  while (isblank(*str))
+     str++;
+
+  for (count = 1, inside = 1; count < field_bool && *str; str++) {
+    if (inside == 1 && isblank(*str))
+      inside = 0;
+
+    if (inside == 0 && !isblank(*str)) {
+      inside = 1;
+      count++;
+    }
+  }
+
+  if (count != field_bool) {
+    printf("Err: field not available\n");
+    return 0;
+  }
+
+  return str - str_og;
+}
-- 
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