SE250:lab-4:hlin079

function int leght

int lenght(Cons*list){
int count=0;
for (;list!=nil;list=list->tail){
  count++;
   }
return count;
}

function element_t nth(inti, Cons*)

element_t nth(int i,Cons*list){
    int count=0;
    for (;list!=nil;list=list->tail){
	if (i!=count){
	    count++;
 }
 else {
	    break;
	}
	
    }
    return list->head;
 }

Equal function

int equal(Cons*list,Cons*list2){
   for(;list!=nil&&list2!=nil;list=list->tail,list2=list2->tail){

if (list->head!=list2->head){

return 0; }

   }
 if (list==list2){

   return 1;
 }
 return 0;
}

find function

Cons*find(element_t q,Cons*list){
   for (;list!=nil;list=list->tail){

if (list->head==q){ return list; }

   }
   return nil;
}

copy function

Cons*copy_list(Cons*list){
   int w= lenght(list);
   int i;
   Cons*list2;
   Cons*start;
   list2=nil;
   for ( i=0;i<w;i++){
   list2=cons(0,list2);
   }
   start=list2;
   for (;list!=nil&&list2!=nil;list=list->tail,list2=list2->tail){

list2->head=list->head;

   }
   return start;
}

first of all, i setup the lenght of list2. After setup the lenght , i used for loop to put each element in the list to list2.

append function

Cons*append(Cons*list,Cons*list2){
   int w= lenght (list)+lenght(list2);
   int i;
   Cons* list3;
   Cons*start1;
   list3=nil;
   for (i=0;i<=w;i++){

list3=cons(0,list3);

   }
   start1=list3;
   for (;list!=nil&&list3!=nil;list=list->tail,list3=list3->tail){
   list3->head=list->head;
   }
for (;list2!=nil&&list3!=nil;list2=list2->tail,list3=list3->tail){
   list3->head=list2->head;
}
return  start1;
}   

at frist i did not set list3 to nil. also i did not have Cons*start when i run the file with the main

int main( ) {
   Cons*list;
   Cons*list2;
   Cons*both;
   print_list(list= cons(1,cons(2,cons(3,nil))) ); /* expect: List[1,2,3] */
   print_list(list2= cons(4,cons(5,cons(6,nil))) );

   both=append(list,list2);  
   print_list(both);
   printf("%d",lenght( cons(1,cons(2,cons(3,nil)))) );
   return 0;
}

it produced an error . after i changed my code the statement.The print_list(both) printed out list[1,2,3,4,5,6,0] i think it was caused by

 for (i=0;i<=w;i++){

list3=cons(0,list3); so i changed my code to

for (i=0;i<w;i++){

list3=cons(0,list3); my new code for the append function is

 int w= lenght (list)+lenght(list2);
   int i;
   Cons* list3;
   Cons*start1;
   list3=nil;
   for (i=0;i<w;i++){

list3=cons(0,list3);

   }
   start1=list3;
   for (;list!=nil&&list3!=nil;list=list->tail,list3=list3->tail){
   list3->head=list->head;
   }
for (;list2!=nil&&list3!=nil;list2=list2->tail,list3=list3->tail){
   list3->head=list2->head;
}
return  start1;
}