Question

Hello, I have this code but its not running like it should:

#include <iostream>
#include <cstdlib>
#include <string>

using namespace std;

class node
{
public:
typedef int data_t;

node *next;
data_t data;

node(data_t d) { next = NULL; data = d; }
};

class linked_list
{
private:
node *head;

public:

linked_list()
{
head = NULL;
}

int size()
{
node *tptr = head;
int c = 0;

while (tptr)
{
c++;
tptr = tptr->next;
}

return c;
}

void add(int n, node::data_t d)
{
node *tptr = head, *prev = head, *curr;
// cout << "add: data = " << d <<"," << "n = " << n << endl;
int c = 0;

if (n < 0)
{
return;
}
if (n == 0)
{
add_first(d);
return;
}
if (size() == n)
{
add_last(d);
return;
}
while (tptr)
{
if (c == n)
{
curr = new node(d);
prev->next = curr;
curr->next = tptr;
break;
}
c++;
prev = tptr;
tptr = tptr->next;
}
}

void add_last(node::data_t d)
{
node *tptr = head;

if (!head)
{
head = new node(d);
return;
}
while (tptr->next)
{
tptr = tptr->next;

}

tptr->next = new node(d);
}

void add_first(node::data_t d)
{

node *newptr = new node(d);
newptr->next = head;
head = newptr;
}

node::data_t get(int n)
{
node *tptr = head;
int c = 0;

if (n == 0)
{
return get_first();
}
if (n == size())
{
return get_last();
}
while (tptr)
{
if (n == c)
{
return tptr->data;
}
tptr = tptr->next;
c++;
}
return tptr->data ;
}

node::data_t get_first()
{
if (!head)
{
cout << "null list\n";
return - 1;
}
return head->data;
}

node::data_t get_last()
{
node *tptr = head;
if (!head)
{
return -1;
}
while (tptr)

{
if (tptr->next == NULL)
{
return tptr->data;
}
tptr = tptr->next;
}
}
void remove(int n)
{
node *tptr = head, *prev = head;
int c=0;

if(n==0)
{
remove_first();
return;
}

if(n==size())
{
remove_last();
return;
}

while(tptr)
{
if(c == n)
{
prev->next = tptr->next;
return;
}
c++;
prev=tptr;
tptr=tptr->next;
}
}

void remove_first()
{
node *new tptr = head;

head = head->next;

delete tptr;
// if(!head)
// {
// return;
// }

// head = head->next;
}

void remove_last()
{
node *tptr = head, *prev = head;

if(!head)
{
return;
}

while(tptr->next != NULL)
{
prev = tptr;
tptr = tptr->next;
}
prev->next = NULL;

}

void dump()
{
node *tptr;

cout << " DUMP: (size = " << size() << ", first = " << get_first() << ", last = " << get_last() << ")\n";

if (head == NULL)
{
cout << " DUMP: head = NULL\n\n";
return;
}

tptr = head;

while (tptr)
{
cout << " DUMP: data = : " << tptr->data << endl;
tptr = tptr->next;
}
cout << endl;
}

};

int main(void)
{

linked_list ll;
string cmd;
int i, d;

while (cin >> cmd >> i >> d)
{
cout << "MAIN: cmd = " << cmd << ", i = " << i
<< ", d = " << d << endl;

if (cmd == "add")
ll.add(i, d);
else if (cmd == "addf")
ll.add_first(d);
else if (cmd == "addl")
ll.add_last(d);
else if (cmd == "rem")
ll.remove(i);
else if (cmd == "remf")
ll.remove_first();
else if (cmd == "reml")
ll.remove_last();
else if (cmd == "get") {
d = ll.get(i);
cout << "get returns: " << d << endl;
} else if (cmd == "getf") {
d = ll.get_first();
cout << "getf returns: " << d << endl;
} else if (cmd == "getl") {
d = ll.get_last();
cout << "getl returns: " << d << endl;
} else if (cmd == "dump")
ll.dump();
else if (cmd == "quit")
exit(0);
}
}
And this is what it should print out, please help, and thank you in advance:

dump 99 et last: invalid index get: invalid index DUMP: (31ze 0, first:-1, last= -1) DUMP: head NULL addf 0 0 add: data 0, n 0 dump 99 DUMP: data addl 2 2 add: data2, n1 dump 9 9 addi, i 2, d 2 DUMP: (size2, first 0, last 2) DUMP: data 0 DUMP: data 2 I add

Answer 1

//Changes have been made. There were some pointer errors and few functions were called in an inappropriate way. Updation done. Please compile and run the following updated code.

linklist.cpp

//preprocessor headers
#include <iostream>
#include <cstdlib>
#include <string>

using namespace std;

//class definition of node
class node
{
public:
typedef int data_t;
node *next;
data_t data;
node(data_t d) { next = NULL; data = d; }
};

//class definition of linkedlist
class linked_list
{
private:
node *head;
public:
linked_list()
{
head = NULL;
}
int size()
{
node *tptr = head;
int c = 0;
while (tptr)
{
c++;
tptr = tptr->next;
}
return c;
}

//function definition to add the node
void add(int n, node::data_t d)
{
node *tptr = head, *prev = head, *curr;
cout << "add: data = " << d <<"," << "n = " << n << endl;
int c = 0;
if (n < 0)
{
return;
}
if (n == 0)
{
add_first(d);
return;
}
if (size() == n)
{
add_last(d);
return;
}
while (tptr)
{
if (c == n)
{
curr = new node(d);
prev->next = curr;
curr->next = tptr;
break;
}
c++;
prev = tptr;
tptr = tptr->next;
}
}

//Function definition to add the node at the last
void add_last(node::data_t d)
{
node *tptr = head;
if (!head)
{
head = new node(d);
return;
}
while (tptr->next)
{
tptr = tptr->next;
}
tptr->next = new node(d);
cout << "add: data = " << d << ", n = " << (size()-1) << endl;
}

//Function definition to add the node at the first
void add_first(node::data_t d)
{
node *newptr = new node(d);
newptr->next = head;
head = newptr;
cout << "add: data = " << d << ", n = " << (size()-1) << endl;
}

//function definition to get the node data
node::data_t get(int n)
{
node *tptr = head;
int c = 0;
if (n == 0)
{
return get_first();
}
if (n == size())
{
return get_last();
}
while (tptr)
{
if (n == c)
{
return tptr->data;
}
tptr = tptr->next;
c++;
}
return tptr->data ;
}

//function definition to get the first node data
node::data_t get_first()
{
if (!head)
{
cout << "null list\n";
return - 1;
}
return head->data;
}

//function definition to get the last node data
node::data_t get_last()
{
node *tptr = head;
if (!head)
{
return -1;
}
while (tptr)
{
if (tptr->next == NULL)
{
return tptr->data;
}
tptr = tptr->next;
}
}

//function definition to remove the data
void remove(int n)
{
node *tptr = head, *prev = head;
int c=0;
if(n==0)
{
remove_first();
return;
}
if(n==size())
{
remove_last();
return;
}
while(tptr)
{
if(c == n)
{
prev->next = tptr->next;
return;
}
c++;
prev=tptr;
tptr=tptr->next;
}
}

//function definition to remove the first data
void remove_first()
{
node *tptr = head;
head = head->next;
delete tptr;
// if(!head)
// {
// return;
// }
// head = head->next;
}

//function definition to remove the last node data

void remove_last()
{
node *tptr = head, *prev = head;
if(!head)
{
return;
}
while(tptr->next != NULL)
{
prev = tptr;
tptr = tptr->next;
}
prev->next = NULL;
}

//function definition to dump the data

void dump()
{
node *tptr;
cout << " DUMP: (size = " << size() << ", first = " << get_first() << ", last = " << get_last() << ")\n";
if (head == NULL)
{
cout << " DUMP: head = NULL\n\n";
return;
}
tptr = head;
while (tptr)
{
cout << " DUMP: data = : " << tptr->data << endl;
tptr = tptr->next;
}
cout << endl;
}
};

int main(void)
{
linked_list ll;
string cmd;
int i, d;
while (cin >> cmd >> i >> d)
{
cout << "MAIN: cmd = " << cmd << ", i = " << i
<< ", d = " << d << endl;
if (cmd == "add")
ll.add(i, d);
else if (cmd == "addf")
ll.add_first(d);
else if (cmd == "addl")
ll.add_last(d);
else if (cmd == "rem")
ll.remove(i);
else if (cmd == "remf")
ll.remove_first();
else if (cmd == "reml")
ll.remove_last();
else if (cmd == "get") {
cout << "get returns: " << ll.get(i) << endl;
} else if (cmd == "getf") {
cout << "getf returns: " << ll.get_first() << endl;
} else if (cmd == "getl") {
cout << "getl returns: " << ll.get_last() << endl;
} else if (cmd == "dump")
ll.dump();
else if (cmd == "quit")
exit(0);
}
}

Output:

Compilation -

Compile Log Debug 88 Compiler Resources dh VDebus laFindResultAciot Compiling single file Abort Compilation - Filename: C:\Users\G priya Darshni\Documents\linklist.cpp Compiler Name: TDM-GCC 4.9.2 64-bit Release Processing C++ source file -C++ Compiler : C:\Program Files (x86ハDer-CppMinGN64\bin\p++.exe Shorten compiler paths Command : "C:\Users\G priya Darshn1\Documents\inklist.cpp" "C:\Users\G priya Darshn1\Documents\linklist .exe " -I"C:\Program Ellea (x86 g++.exe -o Compilation reuits.. - Errors: 0 - Warnings: 0 Output Filename: C:\Users\G priya Darahni\Documents\linklist.exe -Output Size: 1.83896496228027 MiB Compilation Time: 1.28

Execution -

dump , add, add_first and add_last

C:\Users G priya Darshni\ Documentslinklist.exe ump 9 9 IA 1 N :.crnd dump. İ 9, d- ull list DUMP: くsize = 0, first =-1, last = -1〉 DUMP: head = NULL ddf 0 dd : data = 0, n 0 ump 9 9 AIN: cmd = dump, i = 9, DUMP : くsize 1, first- DUMP : data : 0 last 0 ddl 2 2 dd data2. n- 1 ump 9 9 AIN: cmd = dump, i = 9, DUMP: <size -2. first -0 last2> DUMP : data : 0 DUMP data - 2

remove, remove_first and remove_last

addl 4 4 AIN: cmd = add i, i = 4, d = 4 add: data -4. n-1 dump 9 9 AIN: cmd = dump, 1-9, d = 9 DUMP <size -2. first 4. last-4 DUMP: data = : DUMP : data = : 4 4 eml 4 4 dump 9 9 AIN: cmd = dump, i = 9, DUMP: <size -1, first -4, last DUMP: data 4> 4 get 99 MAIN: cnd = get, i = 9, d = 9

get, get_first, get_last

C:\Users G priya Darshni\ Documentslinklist ump 9 9 IA 1 N :.crnd dump. İ 9, d- ull list DUMP: くsize = 0, first =-1, last = -1〉 DUMP: head = NULL AIN: cmd add, 1-0, d = 0 dd : data = 0, n 0 et 0 AIN: cmd get, i = 0, et returns: 0 etf 0 0 etf returns: 0 ddl 4 4 AIN: cmd addi, 1-4, d = 4 dd : data 4, n = 1 etf 1 1 etf returns: 0 etl 11 etl returns: 4 ump 9 9 ge t f , i = 1, d 1 = ge t 1, i 1, d = 1 AIN: cmd = dump, i = 9, DUMP : data : 0 DUMP: data uit 0 AIN: cmd = quit. i-0, d 0 rocess exited after 88.2 seconds with return value ress any key to continue -. .