Unhandled exception in function

[sigutis]

I have this structure;

typedef struct {
    valueType value;
    struct node*pries;
    struct node *po;
} node;

and if I use it in a function like that

node *temp;
temp = (node*)malloc(sizeof(node));
temp->value= 50;

I get a Unhandled exception at 0x00401419 in doubly_linked_list.exe: 0xC0000005: Access violation writing location 0x00000000. runtime error.
However if I use it in the main function it seems to work well. What the f?

[guestgulkan]

Just post your code...

[sigutis]

#include <stdio.h>
#include <stdlib.h>

#define valueType int

typedef struct {
    valueType value;
    struct node*pries;
    struct node *po;
} node;

typedef struct {
    node *first;
    node *last;
} doublyLinkedList;

int pushNode(doublyLinkedList tempList, valueType value) //Prideti prie saraso galo elementa
{
    node *temp;

	temp = (node*)malloc(sizeof(node));
    if (temp = NULL)
        return 0;

	temp->value= value;
        /*etc*/
	return 1;
 }
void initNode(doublyLinkedList temp){
	temp.first=NULL;
	temp.last=NULL;
}

int main()
{
	char a;
	doublyLinkedList oTaip= {NULL,NULL};
	initNode(oTaip);
	pushNode(oTaip,111);
    return 0;
}

[guestgulkan]

Embarrassed to say it took a couple of minutes but the problem is here:

if (temp = NULL) //error using assignment operator

should be:
if (temp == NULL)

[guestgulkan]

Ok - now that we have found the fault - there are some things we could look at (not errors really - more a matter of taste?).

#define valueType int
When creating alias names for types - it is customary to use typedef
So typedef int valueType;

Also:

doublyLinkedList oTaip= {NULL,NULL};
initNode(oTaip); //redundant code - the members of oTaip already initialized in the line above 

[sigutis]

no way! thanks!