From a29d369beed221d0c771f240a8fe8bb8b856f2ac Mon Sep 17 00:00:00 2001
From: Steven Schronk <steven@schronk.com>
Date: Mon, 28 Dec 2009 16:13:23 -0600
Subject: [PATCH] Added example 5-14. Sorts data from stdin. Has some issues.

---
 ex_5-14.c | 162 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 ex_5-14.c

diff --git a/ex_5-14.c b/ex_5-14.c
new file mode 100644
index 0000000..0c56cb6
--- /dev/null
+++ b/ex_5-14.c
@@ -0,0 +1,162 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define MAXLINES 5000   // max number of lines sorted
+#define MAXLEN 1000     // maximum length of each line
+#define ALLOCSIZE 10000 // size of available space
+
+int readlines(char *lineprt[], int nlines);
+void writelines(char *lineprt[], int nlines);
+void new_qsort(void *lineptr[], int left, int right, int (*comp)(void *, void*));
+int numcmp(char *, char *);
+void swap(void *v[], int i, int j);
+int getline(char s[], int lim);
+char *alloc(int n);
+
+char *lineptr[MAXLINES]; // pointers to next lines
+static char allocbuf[ALLOCSIZE];
+static char *allocp = allocbuf;
+
+/*
+
+Get chars ony by one from stdin.  Load them into array of chars within lim.
+
+*/
+int getline(char s[], int lim)
+{
+	int c, i;
+	i = 0;
+	while(--lim > 0 && (c = getchar()) != EOF && c != '\n')
+		s[i++] = c;
+	if(c == '\n')
+		s[i++] = c;
+	s[i] = '\0';
+	return i;
+}
+
+void new_qsort(void *v[], int left, int right, int (*comp)(void *, void*))
+{
+	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((*comp)(v[i], v[left]) < 0)
+			swap(v, ++last, i);
+	swap(v, left, last);
+	new_qsort(v, left, last-1, comp);
+	new_qsort(v, last+1, right, comp);
+}
+
+void swap(void *v[], int i, int j)
+{
+	void *temp;
+	temp = v[i];
+	v[i] = v[j];
+	v[j] = temp;
+}
+
+/*
+
+Compare two strings 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;
+}
+
+/*
+
+read input lines
+
+Use getline to obtain data from stdin.
+
+Put data into array of pointers to char, as long as number of lines less than maxlines.
+
+*/
+int readlines(char *lineprt[], 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;
+}
+
+/*
+write ouput lines to stdout
+
+input is an array of pointers to char and the number of lines stored
+
+ouput goes to stdout
+
+*/
+void writelines(char *lineptr[], int nlines)
+{
+	while(nlines-- > 0)
+		printf("%s\n", *lineptr++);
+}
+
+char *alloc(int n)
+{
+	if(allocbuf + ALLOCSIZE - allocp >= n)
+	{
+		allocp += n;
+		return allocp -n; // old pointer
+	} else {
+		return 0;
+	}
+}
+
+/*
+
+Sort lines in input numerically.
+
+If -n switch entered, sort lines numerically.
+
+Program is limited by buffers of both maximum number of lines and maximum length of lines.
+
+*/
+	
+int main(int argc, char *argv[])
+{
+	int nlines;
+	int numeric = 0;
+
+	if(argc > 1 && strcmp(argv[1], "-n") == 0)
+		numeric = 1;
+	if((nlines = readlines(lineptr, MAXLINES)) >= 0)
+	{
+		new_qsort((void **) lineptr, 0, nlines-1, (int(*)(void *,void *))(numeric ? numcmp : strcmp));
+		writelines(lineptr, nlines);
+		return 0;
+	} else {
+		printf("Input: Too many lines to sort\n");
+		return 1;
+	}
+	return 1;
+}
-- 
2.11.4.GIT