Rhyming Sort text data

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "getopt.h"

#define PACKAGE "rhymsort"
#define VERSION "0.0.2"
#define MAXLINE 1024

struct lnode {
char *str;
struct lnode *next;
};

struct lnode *insert(char *data, struct lnode *list);
void free_list(struct lnode *list);
void print_list(struct lnode *list, int r);
void rev(char *str);
void print_help(int exval);

int main(int argc, char *argv[]) {
FILE *fp = stdin; /* read input from... (default is stdin) */
struct lnode *list; /* linked list */
char line[MAXLINE]; /* buff for fgets() */
int len = 0; /* initial line length */
int opt = 0; /* holds getopt option nr ... */
int min_len = 2; /* minimumn accepted length of incomming lines */
int out_rev_flag = 0; /* output the `raw' reversed lines */
int strip_nl_flag = 0; /* strip trailing newlines from input */

while((opt = getopt(argc, argv, "hvrsn:f:")) != -1) {
switch(opt) {
case 'h':
print_help(0);
break;
case 'v':
exit(0);
break;
case 'r':
out_rev_flag = 1;
break;
case 's':
strip_nl_flag = 1;
break;
case 'n':
min_len = atoi(optarg);
break;
case 'f':
if(freopen(optarg, "r", fp) == NULL) {
fprintf(stderr, "%s: Error - opening `%s'\n", PACKAGE, optarg);
return 1;
}
break;
case ':':
fprintf(stderr, "%s: Error - Option `%c' needs an argument\n\n", PACKAGE, optopt);
print_help(1);
case '?':
fprintf(stderr, "%s: Error - No such option: `%c'\n\n", PACKAGE, optopt);
print_help(1);
} /* switch */
} /* while */

list = NULL;
while((fgets(line, MAXLINE, stdin)) != NULL) {
len = strlen(line);

/* skip lines shorter as ``min_len'' in length */
if(len <>

/* strip trailing newlines */
if(strip_nl_flag == 1 && line[len - 1] == '\n')
line[len - 1] = '\0';

/* reverse line[] buffer */
rev(line);
/* insert line in the linked list */
list = insert(line, list);
}

print_list(list, out_rev_flag);
free_list(list);

fclose(fp);
return 0;
}

struct lnode *insert(char *data, struct lnode *list) {
struct lnode *p;
struct lnode *q;

/* create a new node */
p = (struct lnode *)malloc(sizeof(struct lnode));
/* save data into new node */
p->str = strdup(data);

/* first, we handle the case where `data' should be the first element */
if(list == NULL || strcmp(list->str, data) > 0) {
/* apperently this !IS! the first element */
/* now data should [be|becomes] the first element */
p->next = list;
return p;
} else {
/* search the linked list for the right location */
q = list;
while(q->next != NULL && strcmp(q->next->str, data) <>
q = q->next;
}
p->next = q->next;
q->next = p;
return list;
}
}

void free_list(struct lnode *list) {
struct lnode *p;

while(list != NULL) {
p = list->next;
free(list);
list = p;
}
}

void print_list(struct lnode *list, int r) {
struct lnode *p;

for(p = list; p != NULL; p = p->next)
if(r == 0)
rev(p->str), printf("%s\n", p->str);
else
printf("%s\n", p->str);
}

/* reverse string ... */
void rev(char *str) {
char temp = 0;
char *end = NULL;

/* point to last non-NULL character in str */
end = str + strlen(str) - 1;
while(str <>
temp = *str, *str++ = *end, *end-- = temp;
}

void print_help(int exval) {
printf("%s,%s sort text data by rhyming order\n", PACKAGE, VERSION);
printf("Usage: %s [-h] [-v] [-r] [-s] [-n INT] [-f FILE]\n\n", PACKAGE);

printf(" -h print this help and exit\n");
printf(" -v print version and exit\n\n");

printf(" -r output the `raw' reversed lines\n");
printf(" -s strip trailing newlines\n");
printf(" -n INT ignore lines shorter as `INT' (default=2)\n");
printf(" -f FILE read input from `FILE' (default=stdin)\n\n");

exit(exval);
}

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