Why my code can not produce linked list

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I wrote two codes to produce linked list.

One code uses insert function to form linked list.
Other code does not uses insert function for this.

There are no compiler errors in either of them.

BUT the code with insert function is giving BLANK SCREEN when I run the program where as the other code works well

Please help me figure this out and solve my problem.

What I have tried:

C++

#include <iostream>

using namespace std;

struct node{
int data;
node*next;
};
node*head=NULL;
node* insert_(node*head,int size)
{

    for (int i=0;i<size;i++)>
    {
        node*temp=new node;
        temp->data=i;
        temp->next=head;
        head=temp;
        return head;
        }
}
int main()
{
insert_(head,4);
while(head)
{
    cout << head->data ;
    head=head->next;
}
}

CODE WITHOUT INSERT FUNCTION(which works well)

C++

#include <iostream>

using namespace std;

struct node{
int data;
node*next;
};
node*head=NULL;

int main()
{
for (int i=0;i<5;i++)
    {
        node*temp=new node;
        temp->data=i;
        temp->next=head;
        head=temp;

        }



while(head)
{
    cout << head->data  ;
    head=head->next;
}
}

Posted 14-Jun-16 0:27am

Member 12566145

Updated 14-Jun-16 6:51am

Matt T Heffron

v3

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CHill60 14-Jun-16 6:36am

Did you try debugging to see what is going on?

2 solutions

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Jochen Arndt · Accepted Answer · 2016-06-14T00:39:00

In the insert version you are passing head as parameter using the same name as your global variable. Because it is a function, the local (parameter) variable is used and the content of the global variable is left unchanged.

In the second version the global variable is used and modified.

To get similar behaviour assign the return value of the insert function to your global variable:

head = insert_(head,4);

[EDIT]
And of course the error reported in solution 1 which I did not saw because the code was initially not formatted.
[/EDIT]

xszaboj · Accepted Answer · 2016-06-14T00:39:00

Solution 1

I think it is because you have return in for cycle, but i guess it should be out of it.
like this:

C#

for (int i=0;i<size;i++)>
    {
        node*temp=new node;
        temp->data=i;
        temp->next=head;
        head=temp;
        
        }
return head;

Posted 14-Jun-16 0:39am

xszaboj

Comments

Member 12566145 14-Jun-16 6:53am

thanks for you help :-)