Thread: SORRY need my hand holding with linked lists

Not sure if my program is safe to run,please comment on my comments and please get my program running where I can input the amount of nodes at run time.

#include<string.h>
#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
#define MAX 30

struct node{
int age;
char name[MAX];
node *next;
};


int main()
{
int amount;

cout<<"How many people to be stored";
cin>>amount;

node *ptr=(node*)malloc(sizeof(node)); /* does'nt this need to be sizeof(node) * amount */
/* because we need a block of memory for each node */
strcpy(ptr->name,"ANTHONY");
cout<<ptr->name;

for(int start=0;start<amount;start++)
{
ptr->next=(node*)malloc(sizeof(node)); /* is this correct */
ptr->next; /* and this */
/* do something with nodes here */
free(node ptr[start]); /* how do I free the node pointers individually/altogether */
}
ptr=NULL; /* is this needed */

getch();

return 0;
}

BIG thanks for this.

Code:

#include<cstring>
#include<iostream>
#include<cstdlib>

#define MAX 30

struct node
{
  int age;
  char name[MAX];
  node *next;
};

int main ()
{
  int amount;
  cout << "How many people to be stored"<<endl;
  cin >> amount;
  node *ptr = (node *) malloc (sizeof (node));	/* does'nt this need to be sizeof(node) * amount */
  // No

  /* because we need a block of memory for each node */

  // You cannot allocate space for the nodes behind that "node *next" like that.
  
  strcpy (ptr->name, "ANTHONY");
  std::cout << ptr->name << std::endl;
  for (int start = 0; start < amount; start++) {
    ptr->next = (node *) malloc (sizeof (node));	/* is this correct */
    // Yes, but new is usually used if you are using C++.
    ptr->next;		/* and this */
    // This does not do anything.
    // Do you mean ptr=ptr->next; ?

    /* do something with nodes here */
    
    free (ptr[start]);	/* how do I free the node pointers individually/altogether */
    // Like this, but it is not very wise to it here because you are using it again on the next
    // round in the loop
  }
  ptr = NULL;			/* is this needed */

  // Well, it's recommended to avoid problems later

  return 0;
}

#include<string.h>
#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
#define MAX 30

struct node{
int age;
char name[MAX];
node *next;
};


int main()
{
//declare a single node, not associated with list yet
//I'm using C++, not C so you'll have to do the changes there
node *ptr= new node;
strcpy(ptr->name,"ANTHONY");
cout<<ptr->name;

//now delete/free the memory just assigned to ptr
delet ptr;
ptr = NULL;

//now work with a list

node * head = NULL;
//to keep track of the first node in the list. If you don't keep track of the first node you will never be able to find the others either, because the only way you know where to find nodes subsequent to head is by looking at the next pointer in the current node.

//ptr will be used to keep track of where we are in the list

node * newNode;
//newNode will be used to get the new memory to be added to the list


int amount;

cout<<"How many people to be stored";
cin>>amount;

//add a given number of nodes to a list at the tail of the list each time

for(int start=0;start<amount;start++)
{
//each loop will add one node
newNode = new node;
//assign data to newNode here;

//assign newNode to head if head is still NULL
if(head == NULL)
{
head = newNode;
}
else
{
//assign newNode to the end of the list
//find the end of the list first
//start at head each time
ptr = head;
//when ptr->next == NULL you have found the last node in the list
while(ptr->next != NULL)
{
ptr = ptr->next;
}
//now assign newNode to ptr->next
ptr->next = newNode;
}


//delete the list in any order you want;
//typically find the last node in the list and delete it OR
//delete the first node each time, like below
ptr = head;
while(ptr != NULL)//as
{
head = head->next;//keep track of the "new" first node!
delete ptr;
ptr = head;
}

getch();

return 0;
}

When you know how to do your own list, stop reinventing the weel and use the std::list instead... easy, painless, optimized, portable...