Endless loop recording string - c++

Question

The code should create a doubly linked list. THen a list of IP adresses should be added to this list with the number of times the unique IP is met. Then the list should be sorted. TO my sorry, the code is cycled somewhere when it's recorded. Highlighted the place in bold (tried to do that:)).
P.S. I would be pleased if you'll help me with sort method selection. I've already made one, but what would be better to use quicksort or something else?
#include <stdlib.h>
#include <iostream>
#include <stdio.h>
using namespace std;
struct IP
{
char b[20];
int count;
};
struct Node
{
IP a;
Node *Next,*Prev;
};
struct List
{
Node *Head,*Tail;
int length;
List():Head(NULL),Tail(NULL){};
};
List* list_new()
{
return (List *)calloc(1, sizeof(List));
}
void list_delete(List* l)
{
while (l->Head)
{
l->Tail=l->Head->Next;
free (l->Head);
l->Head=l->Tail;
}
l->length=0;
}
bool push(List* l, IP a)
{
Node *temp=(Node* ) calloc (1, sizeof(Node));
temp->Next=NULL;
temp->a=a;
if (l->Head!=NULL)
{
temp->Prev=l->Tail;
l->Tail->Next=temp;
l->Tail=temp;
}
else
{
temp->Prev=NULL;
l->Head=l->Tail=temp;
}
return 1;
}
bool pop(List*l, IP* x)
{
(*x)=l->Tail->a;
l->Tail->Prev->Next=NULL;
l->Tail=l->Tail->Prev;
l->length++;
return 1;
}
bool unshift(List*l, IP a)
{
Node *temp=(Node* ) calloc (1, sizeof(Node));
temp->Next=NULL;
temp->a=a;
if (l->Head!=NULL)
{
temp->Next=l->Head;
l->Head->Prev=temp;
l->Head=temp;
}
else
{
temp->Prev=NULL;
l->Head=l->Tail=temp;
}
return 1;
}
bool shift(List* l, IP* x)
{
(*x)=l->Head->a;
l->Head->Next->Prev=NULL;
l->Head=l->Head->Next;
return 1;
}
bool reverse (List* l)
{
Node* temp=l->Head;
Node* swaps=NULL;
l->Tail=l->Head;
while (temp!=NULL)
{
swaps=temp->Prev;
temp->Prev=temp->Next;
temp->Next=swaps;
temp=temp->Prev;
}
if (swaps != NULL) l->Head = swaps->Prev;
return 1;
}
void sort (List* l)
{
int i;
for (i=0; i<l->length; ++i) {
Node* compared = l->Head;
while (compared->Next != NULL) {
if (compared->Next->a.count > compared->a.count) {
IP t = compared->Next->a;
compared->Next->a = compared->a;
compared->a = t;
}
compared = compared->Next;
}
}
}
void Show(List* l)
{
int i;
Node* temp=l->Head;
while (temp!=NULL)
{
cout<<temp->a.b<<" "<<temp->a.count<<"\n";
temp=temp->Next;
}
cout<<"\n";
}
int main ()
{
int i;
char strbuf[1000],chTemp;
IP ipTemp;
bool met;
system("CLS");
List* l = list_new();
FILE* foo;
errno_t err;
err=fopen_s(&foo,"input.txt","r");
if( err == 0 )
{
printf( "The file 'input.txt' was opened\n" );
}
else
{
printf( "The file 'input.txt' was not opened\n" );
}
while (!feof(foo))
{
fgets(strbuf,1000,foo);
fclose(foo);
for (i=0;i++;i<20)
if (strbuf[i]==' ') {strncpy_s( ipTemp.b,strbuf, i);break;}
Node* cur = l->Head;
met=0;
while (cur!=NULL)
{
if (cur->a.b == ipTemp.b)
{
met=1;
cur->a.count++;
break;
}
cur=cur->Next;
}
if (met==0)
{
push(l,ipTemp);
l->Tail->a.count++;
}
}
sort(l);
Show(l);
system("PAUSE");
}

Answer 1

If the code had a cleaner indentation, you would maybe realize that the logic is wrong:
while (!feof(foo))
{
fgets(strbuf,1000,foo); // <-- what if fgets hits EOF or error occurs?
fclose(foo); // <-- why?
for (i = 0; i++; i < 20) // <-- i++ is always true ~> infinite loop
....
...
}
should be (assuming you want to write code in C):
while (fgets(strbuf, 1000, foo))
{
for (i = 0; i < 20; i++)
....
...
}

Answer 2

for (i=0;i++;i<20) should be for (i=0;i<20;i++)