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#include <stdio.h>
#include <string.h>
#define MAXLINES 5000
#define MAXLEN 1000
char line[MAXLINES][MAXLEN]; /* same as `char (line[MAXLEN])[MAXLINES]` */
/* we are using a lineptr here because array `line` pointer is const like all arrays and there addreses cant be changed to sort them only values can be exchanged
* but copying each char back and forth would take up more resources and using a lineptr is much more efficent, here we are not actully sorting line itself
* but sorting pointers in lineptr to reflect the order*/
char *lineptr[MAXLINES]; /* same as `char *(lineptr[MAXLINES])` */
int readlines(char *lineptr[], int max);
void writelines(char *lineptr[], int max);
void my_qsort(char *lineptr[], int left, int right);
int
main(void)
{
int nlines;
if ((nlines = readlines(lineptr, MAXLINES)) > 0) {
my_qsort(lineptr, 0, nlines);
writelines(lineptr, nlines);
return 0;
} else {
printf("Err: lines, lines everywhere\n"); /* too much lines / input too big */
return 1;
}
return 0;
}
int sneed_getline(char str[], int max);
int
readlines(char *lineptr[], int max)
{
int len, nlines;
for (nlines = 0; (len = sneed_getline(line[nlines], MAXLEN)) > 0; nlines++) {
if (nlines < max) {
lineptr[nlines] = line[nlines];
}
else
return -1;
}
return nlines;
}
void
writelines(char *lineptr[], int max)
{
while (max--)
printf("%s\n", *lineptr++);
}
int
sneed_getline(char str[], int max)
{
char input;
char *str_og;
str_og = str;
--max;
while (--max && (input = getchar()) != EOF && input != '\n')
*str++ = input;
/*
if (input == '\n' && max)
*str++ = input; */
*str = '\0';
return str - str_og;
}
void swap(char *lineptr[], int to, int from);
void
my_qsort(char *lineptr[], int left, int right)
{
int i, last;
if (left >= right)
return;
swap (lineptr, left, (left+right)/2);
last = left;
for (i = left+1; i < right; i++)
if (strcmp(lineptr[i], lineptr[left]) < 0)
swap(lineptr, i, ++last);
swap(lineptr, left, last);
my_qsort(lineptr, left, last - 1);
my_qsort(lineptr, last + 1, right);
}
void
swap(char *lineptr[], int to, int from)
{
char *temp;
temp = lineptr[to];
lineptr[to] = lineptr[from];
lineptr[from] = temp;
}
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