added Exercise 5-15

Author: satyajitghana

Chapter-5/Exercise 5-14/main.c

@@ -35,7 +35,9 @@ int main(int argc, char **argv) {
                     }
     }
     if (argc != 0) {
-        printf("Usage: %s -n -r\n", name);
+        printf("Usage: %s -n -r\n"
+                "n: numeric sort\n"
+                "r: reverse sort\n", name);
         return 0;
     }
     //return 0;

Chapter-5/Exercise 5-15/alloc.c

@@ -0,0 +1,18 @@
+#define ALLOCSIZE 10000 /* size of available space */
+
+static char allocbuf[ALLOCSIZE]; /* storage for alloc */
+static char *allocp = allocbuf;  /* next free position */
+
+char *alloc(int n) /* return pointer to n characters */{
+    /* end of the allocbuf - allocp should be >= n for it to fit */
+    if (allocbuf + ALLOCSIZE - allocp >= n) { /* it fits */
+        allocp += n;
+        return allocp-n; /* old pointer */
+    } else
+        return 0;
+}
+
+void afree(char *p) /* free storage pointed to by p */ {
+    if (p >= allocbuf && p < allocbuf + ALLOCSIZE)
+        allocp = p;
+}

Chapter-5/Exercise 5-15/alloc.h

@@ -0,0 +1,8 @@
+#ifndef ALLOC_H
+#define ALLOC_H
+
+char *alloc(int n);
+
+void afree(char *p);
+
+#endif

Chapter-5/Exercise 5-15/main.c

@@ -0,0 +1,115 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "my_io.h"
+#include "alloc.h"
+
+#define MAXLINES 5000
+char *lineptr[MAXLINES];
+
+void _qsort(void *lineptr[], int left, int right, int (*comp)(void *, void *), int order);
+
+int numcmp(char *, char *);
+int strcmpi(char *, char *);
+
+int main(int argc, char **argv) {
+    int numeric = 0;
+    //int reverse = -1;
+    int order = 1;
+    int ignore_case = 0;
+    char *name = *argv;
+    char c;
+    /*if (argc > 1 && strcmp(*++argv, "-n") == 0) 
+        numeric = 1;*/
+    while (--argc > 0 && **++argv == '-') {
+        while (c = *++(*argv))
+                switch(c) {
+                    case 'n':
+                        numeric = 1;
+                        break;
+                    case 'r':
+                        order *= -1;
+                        break;
+                    case 'f':
+                        ignore_case = 1;
+                        break;
+                    default:
+                        printf("%s: illegal character %c\n", name, c);
+                        argc = -1;
+                        break;
+                    }
+    }
+    if (argc != 0) {
+        printf("Usage: %s -n -r\n"
+                "n: numeric sort\n"
+                "r: reverse sort\n"
+                "f : fold (ignore case)\n", name);
+        return 0;
+    }
+    //return 0;
+    int nlines;
+    if ((nlines = readlines(lineptr, MAXLINES)) >= 0) {
+        _qsort((void **) lineptr, 0, nlines-1, (int (*)(void*, void*))(numeric ? numcmp : ((ignore_case) ? strcmpi : strcmp)), order);
+        writelines(lineptr, nlines);
+        return 0;
+    } else {
+        printf("input too big to sort\n");
+        return 1;
+    }
+    return 0;
+}
+
+/* qsort: sort v[left]...v[right] into increasing order */
+void _qsort(void *v[], int left, int right, int (*comp)(void *, void *), int order) {
+    int i, last;
+    void swap(void *v[], int, int);
+
+    if (left >= right) return;
+    swap(v, left, (left + right) / 2);
+    last = left;
+    for (i = left + 1 ; i <= right ; i++)
+        if ((order)*(*comp)(v[i], v[left]) < 0)
+            swap(v, ++last, i);
+    swap(v, left, last);
+    _qsort(v, left, last - 1, comp, order);
+    _qsort(v, last + 1, right, comp, order);
+}
+
+/* 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;
+}
+
+int strcmpi(char *s1, char *s2) {
+    void strupr(char *);
+
+    char v1[1024], v2[1024];
+    strcpy(v1, s1);
+    strupr(v1);
+    strcpy(v2, s2);
+    strupr(v2);
+
+    return strcmp(v1, v2);
+}
+
+void strupr(char *s) {
+    while(*s != '\0') {
+        if (*s >= 'a' && *s <= 'z')
+            *s = 'A' + (*s-'a');
+        s++;
+    }
+}
+
+void swap(void *v[], int i, int j) {
+    void *temp;
+    temp = v[i], v[i] = v[j], v[j] = temp;
+}

Chapter-5/Exercise 5-15/my_io.c

@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <string.h>
+#include "alloc.h"
+#define MAXLEN 1000 /* max length of any input line */
+
+int _getline(char str[], int lim) {
+    int c, i = 0;
+    while (--lim && (c = getchar()) != EOF && c != '\n')
+        str[i++] = c;
+    if (c == '\n') str[i++] = c;
+    str[i] = '\0';
+
+    return i;
+}
+
+/* readlines: read input lines */
+int readlines(char *lineptr[], int maxlines) {
+    int len, nlines;
+    char *p, line[MAXLEN];
+
+    nlines = 0;
+    while ((len = _getline(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;
+}
+
+/* _readlines: doesn't use the alloc for memory allocation */
+int _readlines(char *lineptr[], int maxlines, char *linestore) {
+    int len, nlines;
+    char line[MAXLEN];
+    while ((len = _getline(line, MAXLEN)) > 0) {
+        if (nlines >= maxlines)
+            return -1;
+        else {
+            line[len-1] = '\0'; /* delete the newline */
+            strcpy(linestore, line);
+            lineptr[nlines++] = linestore;
+        }
+        linestore += len;
+    }
+    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]);
+}

Chapter-5/Exercise 5-15/my_io.h

@@ -0,0 +1,11 @@
+#ifndef MY_IO_H
+#define MY_IO_H
+
+int _getline(char str[], int limit);
+
+int _readlines(char *lineptr[], int maxlines, char *linestore);
+int readlines(char *lineptr[], int maxlines);
+
+void writelines(char *lineptr[], int nlines);
+
+#endif