Added example 5-14. Sorts data from stdin. Has some issues.

diff --git a/ex_5-14.c b/ex_5-14.c
new file mode 100644 (file)
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;
+}