Question

This suppose to be an easy link list problem, but when I add input_info() to the main() function, MSVC cl compiler gives me error msg like this:

syntax error : missing ';' before 'type'
error C2065: 'first_ptr' : undeclared identifier
warning C4047: 'function' : 'struct linked_list *' differs in levels of indirection from 'int '
warning C4024: 'print_list' : different types for formal and actual parameter 1

I don’t understand why compiler is showing me error like this… Please let me learn about why MSVC 6.0 compiler is giving me error msg like this.

/*
*
*     this program is a simple link list which will have add(), 
*   remove(), find(), and tihs link list will contains the student 
*   information. 
*         
*/

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

//this ppl structure student holds student info
typedef struct 
{

    char *name;
    int height;
    int weight;

}ppl;

//this structure is the link list structure
typedef struct linked_list
{
    ppl data;
    struct linked_list *next_ptr;
} linked_list;

//this function will print the link list in a reversed order
void print_list(linked_list *a)
{

    linked_list *llp=a;
    while (llp!=NULL)
    {
    printf("name: %s, height: %d, weight: %d \n",llp->data.name,llp->data.height,llp->data.weight);
        llp=llp->next_ptr;

    }
}

//this function will add ppl info to the link list
void add_list(ppl a, linked_list **first_ptr)
{
    //new node ptr
    linked_list *new_node_ptr;
    //create a structure for the item
    new_node_ptr=malloc(sizeof(linked_list));

    //store the item in the new element
    new_node_ptr->data=a;
    //make the first element of the list point to the new element
    new_node_ptr->next_ptr=*first_ptr;

    //the new lement is now the first element
    *first_ptr=new_node_ptr;
 }

void  input_info(void)
{
    printf("Please input the student info!\n");
}


int main()
{   
    ppl a={"Bla",125,11};

    input_info();
    //first node ptr
    struct linked_list *first_ptr=NULL;

    //add_list(a, &first_ptr);
    printf("name: %s, height: %d, weight: %d \n",a.name,a.height,a.weight);

    //print link list
    print_list(first_ptr);  
    return 0;
}

Answer 1

Since you’re comiling in MSVC which is strictly C89, you can’t mix declarations, and code, so

input_info();
struct linked_list *first_ptr=NULL;

Doesn’t work, since after input_info(); The compiler sees a type, which it shouldn’t, since you can’t declare anything there. Simply change that to:

struct linked_list *first_ptr=NULL;
input_info();

And everything should work.