THE LONGEST THREAD.
- Thread starter Nightbreed
- Start date
Code:
/*
* Assignment3-Operations on Lists.
* Functional approaches. Recursive.
*/
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
typedef int boolean;
typedef char data;
typedef struct node
{
data info;
struct node *next;
}list_node;
typedef list_node list_head;
typedef list_head *list;
list L;
list nullist() /* return an empty list */
{
L=(list_head *)malloc(sizeof *L);
L->next=NULL;
return(L);
}
boolean null(list L) /* Test an empty list */
{
return (L->next== NULL);
}
data car(list L) /* obtain the first element of given list */
{
return (L->next->info);
}
list cdr(list L) /* obtain the rest of the list */
{
list_head *cdr_head;
cdr_head=nullist();
cdr_head->next = L->next->next;
return (cdr_head);
}
list cons(data alpha, list L) /* insert an element into a list */
{
list_node *insert=nullist();
list_head *cons_head=nullist();
insert->info = alpha;
insert->next = L->next;
cons_head->next = insert;
return (cons_head);
}
data read_element() /* to skip spaces */
{
data letter;
letter = getchar();
while(isspace(letter)) letter=getchar();
return(letter);
}
list readlist_element(void) /* to read in elements */
{
data letter;
letter = read_element();
if (letter == ')')
return(nullist());
else
return(cons(letter, readlist_element()));
}
list readlist(void) /* to start reading a list */
{
data letter;
letter = read_element();
if (letter == '(')
return(readlist_element());
else if(isalpha(letter)||(48<=letter&&57>=letter))
printf("Error on input format. \n");
return(0);
}
void print(list L){ /* to print out a list */
if(null(L))
printf(")\n");
else
{
printf("%c", car(L));
printf(" ");
print(cdr(L));
}
}
void printlist(list L)
{
printf("(");
printf(" ");
print(L);
}
int length(list L){ /* Returns the number of elements in the list */
if(null(L)) return 0;
else
return 1+length(cdr(L));
}
list append(list L1, list L2){ /* Returns the concatenation of two lists */
if(null(L1))
return L2;
else return
cons(car(L1), append(cdr(L1), L2));
}
list reverse(list L) /* Returns the reverse of a list */
{if(null(L)) return nullist();
else return
append(reverse(cdr(L)), cons(car(L), nullist()));
}
main()
{
list one;
list two;
list ap, rv1, rv2;
/* Get lists */
printf("Enter first list>>");
one=readlist();
printf("Enter second list>>");
two=readlist();
/* Display list one */
printf("First list : ");
printlist(one);
printf("Length = %d\n", length(one));
rv1=reverse(one);
printlist(rv1);
printf("\n");
/* Display list two */
printf("Second list : ");
printlist(two);
printf("Length = %d\n", length(two));
rv2=reverse(two);
printlist(rv2);
/* Append two lists */
ap=append(one, two);
printf("Append : ");
printlist(ap);
}Well someone else found it but
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http://www.siccness.net/vb/showthread.php?s=&threadid=5832&perpage=15&pagenumber=1
