1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
|
#include <stdio.h>
#include <string.h>
#include <stdlib.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 quicksort(void *lineptr[], int left, int right, int (*comp)(void *, void *));
int numcmp(const char *, const char *);
/* sort input lines */
int main(int argc, char *argv[])
{
int nlines; /* number of input lines read */
int numeric = 0; /* 1 if numeric sort */
if (argc > 1 && strcmp(argv[1], "-n") == 0)
numeric = 1;
if ((nlines = readlines(lineptr, MAXLINES)) >= 0) {
quicksort((void **) lineptr, 0, nlines-1, (int (*)(void *, void *)) (numeric ? numcmp : strcmp));
writelines(lineptr, nlines);
return 0;
} else {
printf("input too big to sort\n");
return 1;
}
}
/* qsort: sort v[left]...v[right] into increasing order */
void quicksort(void *v[], int left, int right, int (*comp) (void *, void*))
{
int i, last;
void myswap(void *v[], int, int);
if (left >= right) /* do nothing if array contains */
return /* fewer than two elements */
myswap(v, left, (left + right)/2);
last = left;
for (i = left+1; i<= right; i++)
if ((*comp) (v[i], v[left]) < 0)
myswap(v, ++last, i);
myswap(v, left, last);
quicksort(v, left, last-1, comp);
quicksort(v, last+1, right, comp);
}
/* numcmp: compare s1 and s2 numerically */
int numcmp(const char *s1, const 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 myswap(void *v[], int i, int j)
{
void *temp;
temp = v[i];
v[i] = v[j];
v[j] = temp;
}
#define MAXLEN 1000 /* max length of any input line */
int mygetline(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 = mygetline(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;
}
void writelines(char *lineptr[], int nlines)
{
int i;
for (i = 0; i < nlines; i++)
printf("%s\n", lineptr[i]);
}
int mygetline (char s[], int lim)
{
int c, i;
for (i = 0; i<lim-1 && (c=getchar()) != EOF && c!= '\n'; ++i)
s[i] = c;
if (c == '\n') {
s[i] = c;
++i;
}
s[i] = '\0';
return i;
}
#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 */
{
if (allocbuf + ALLOCSIZE - allocp >= n) { /* it fits */
allocp += n;
return allocp - n; /* old p */
} else /* not enough room */
return 0;
}
|
