一. 程序功用
一起,假如传递了-r参数,则降序, 不然升序.
二. 程序源码
#include
#include
#include
#include
#define DECR 2
#define FOLD 4
#define MAXLINES 5000
#define MAXLEN 1000
#define MAXSTORAGE 10000
char *lineptr[MAXLINES];
char lines[MAXSTORAGE];
int charcmp(char *, char *);
int numcmp(char *, char *);
int p_realines(char *lineptr[], int maxlines);
void p_qsort(void *v[], int left, int right, int(*comp)(void *, void *));
void p_writelines(char *lineptr[], int nlines, int order);
static char option = 0;
int main(int argc, char *argv[])
{
int nlines;
int c, rc = 0;
while (–argc > 0 && (*++argv)[0] == -)
{
while (c = *++argv[0])
{
switch(c) {
case f:
option |= FOLD;
break;
case n:
break;
case r:
option |= DECR;
break;
default:
printf(“sort: illegal option %c\n”, c);
argc = 1;
rc = -1;
break;
}
}
}
if (argc)
printf(“Usage: sort -fnr\n”);
else {
if ((nlines = p_readlines(lineptr, MAXLINES)) > 0) {
p_qsort((void **)lineptr, 0, nlines-1,(int (*)(void *, void *))numcmp);
else if (option & FOLD)
p_qsort((void **)lineptr, 0, nlines-1,(int (*)(void *, void *))charcmp);
else
p_qsort((void **)lineptr, 0, nlines-1, (int (*)(void *, void *))strcmp);
p_writelines(lineptr, nlines, option & DECR);
} else {
printf(“Input too big to sort!\n”);
rc = -1;
}
}
system(“pause”);
return rc;
}
int charcmp(char *s, char *t)
{
for (; tolower(*s) == tolower(*t); s++, t++)
if (*s == \0)
return 0;
return tolower(*s) – tolower(*t);
}
int p_readlines(char *lineptr[], int maxlines)
{
int len, nlines;
char *p = lines, line[MAXLEN];
nlines = 0;
printf(“Please input a string(# to end input): “);
while ((len = getline(line, MAXLEN)) > 0)
{
if (strcmp(line, “#\n”) == 0)
break;
if (nlines >= maxlines || p + len >= lines + MAXSTORAGE)
return -1;
else {
line[len – 1] = \0;
strcpy(p, line);
lineptr[nlines++] = p;
p += len;
}
printf(“Please input a string(# to end input): “);
}
return nlines;
}
void p_writelines(char *lineptr[], int nlines, int order)
{
int i;
if (order)
for (i = nlines -1; i >= 0; i–)
printf(“%s\n”, lineptr[i]);
else
for (i = 0; i < nlines; i++)
printf(“%s\n”, lineptr[i]);
printf(“\n”);
}
void swap(void *v[], int i, int j)
{
void *temp;
temp = v[i];
v[i] = v[j];
v[j] = temp;
}
int getline(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;
}
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;
}
void p_qsort(void *v[], int left, int right, int(*comp)(void *, void *))
{
int i, last;
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);
p_qsort(v, left, last – 1, comp);
p_qsort(v, last + 1, right, comp);
}
