Thread: segmentation error!

I need some help here.

basically i have a linked list of strings of the following format.

"integer operator integer ...="

it will contain atleast 2 integers but can be of varied length.

head->expression contains the string. I'm trying to calculate the sum and print it along the string.

Code:

void printQueue(struct node *head)
{
        char *del = " =";
        char* token;
        char* op;
        int sum = 0;
        while(head != NULL)
        {


                token = strtok(head->expression,del);
                while(token!=NULL)
                {
                        op = strtok(NULL,del);


                        if (strcmp(op,"+")==0)
                        {
                                sum = atoi(token) + atoi(strtok(NULL,del));
                        }
                        else if (strcmp(op,"-") == 0)
                        {
                                sum = atoi(token) - atoi(strtok(NULL,del));
                        }




                }
        printf("%s %d\n", head->expression,sum);
        head = head->next;
        sum = 0;
}
}

I'm getting seg fault or just plain blank output.

works fine if i just print the strings.