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2008-11-03T05:19:38Z

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= Lab4 =
This Lab are all about Linked list.

Start code from LL.c
Use Test code from test-code.c

= task1 =
use funtion '''int Length(Cons*)''' to return the number of elements in the list
==code==
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
typedef int element_t;
typedef
struct Cons {
element_t head;
struct Cons* tail;
} Cons;
static Cons NIL = { 0, &NIL };
Cons* nil = &NIL;
Cons* cons( element_t elt, Cons* tail ) {
Cons* cell = malloc( sizeof(Cons) );
assert( cell != 0 );
cell->head = elt;
cell->tail = tail;
return cell;
}
int length(Cons* list){
int length=0;
for (; list!=nil; list=list->tail){
length++;
}
return length;
}
int main( ) {
print_list( cons(1,cons(2,cons(3,nil))) ); /* expect: List[1,2,3] */
assert( length( nil ) == 0 );
assert( length( cons(10,cons(20,cons(30,nil))) ) == 3 );
return 0;
}

for the '''funtion length''' need to check the list not equal to nil and list = list->tail.

= task2 =
write functions ''' element_t first(Cons*), element_t second(Cons*), element_t third(Cons*), element_t fourth(Cons*)''' that return the element in the named position.
==code==
element_t first(Cons* list){
return list->head;
}
element_t second(Cons* list){
return list->tail->head;
}
element_t third(Cons* list){
return list->tail->tail->head;
}
element_t fourth(Cons* list){
return list->tail->tail->tail->head;
}

test code is

assert( first( nil ) == 0 );
assert( first( cons(10,cons(20,nil)) ) == 10 );
assert( second( nil ) == 0 );
assert( second( cons(10,cons(20,nil)) ) == 20 );
assert( third( nil ) == 0 );
assert( third( cons(10,cons(20,nil)) ) == 0 );
assert( third( cons(10,cons(20,cons(30,nil))) ) == 30 );
assert( fourth( nil ) == 0 );
assert( fourth( cons(10,cons(20,nil)) ) == 0 );
assert( fourth( cons(10,cons(20,cons(30,nil))) ) == 0 );
assert( fourth( cons(10,cons(20,cons(30,cons(40,nil)))) ) == 40 );

because the code has
static Cons NIL = { 0, &NIL };
so dont need to check that whether the tail is equal to nil.

= task3 =
write a funtion '''element_t nth(int i,Cons*)''' the return the i'th element of a list. or 0 if no such element exists.
==code==
element_t nth(int i,Cons* list){
int n;
if( length(list)<i){
return 0;
}
for(n=1;n<=i;n++){
list = list->tail;
}
return list->head;
}

this task is need to check that whether ''i '' is bigger than the length of the Cons* and return the element.

= task4 =
write a funtion '''int equal(Cons*,Cons*)''' that returns true(1)if both list have exactly the same elements in same order,false(0) otherwise.
==code==

= task5 =
write a funtion '''Cond* find(element_t,Cons*)''' to search for an element in list and return the Cons cell that contains this value,or the empty list if i does not occour in the list.
==code==

= task6 =
==code==
= task7 =
==code==

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Mark: 21 revision(s)