Linked lists in C, how to fix expected identifier error?

Question

I am new to C and I can't get this thing to compile properly, can you help me?

struct tagNode
{
    int v, f;

    struct tagNode *next;

    struct tagNode( int _v )
    {
        v = _v;
        next = NULL;
    }
};

expected identifier or ‘(’ before ‘int’: struct tagNode( int _v )

If this is supposed to be C, then you can't put functions inside structure definitions - only declarations. — Tom Karzes, Jun 01 '19 at 08:45
@StoryTeller And not even valid C++. Constructors can't have the `struct` or `class` keyword in their declaration. — Some programmer dude, Jun 01 '19 at 08:58
@makc2099 Please take some time to read [the help pages](http://stackoverflow.com/help), take [the SO tour](http://stackoverflow.com/tour), read about [how to ask good questions](http://stackoverflow.com/help/how-to-ask), as well as [this question checklist](https://codeblog.jonskeet.uk/2012/11/24/stack-overflow-question-checklist/). — Some programmer dude, Jun 01 '19 at 09:00

score 0 · Accepted Answer · answered Jun 01 '19 at 09:13

expected identifier or ‘(’ before ‘int’: struct tagNode( int _v )

this is because of the unexpected struct when you compile in C++

A valid version of your code in C++ can be:

struct tagNode
{
    int v, f;

    tagNode *next;

    tagNode (int _v)
    {
        v = _v;
        next = NULL;
    }
};

but

what about f ?
the constructor can also be tagNode(int _v) : v(_v), next(NULL) {}
and you have a pointer so I recommend you to look at the rule of three

There is no constructor/methods in C so the equivalent of your code in C can be :

#include <stdlib.h>

struct tagNode
{
  int v, f;
  struct tagNode * next;
};

struct tagNode * alloc(int _v)
{
  struct tagNode * r = malloc(sizeof(struct tagNode));

  r->v = _v;
  r->next = NULL;
  return r;
}

Linked lists in C, how to fix expected identifier error?

1 Answers1