Pointer to structure in C

[Jamaima]

I have a little concern at the use of <sys/stat.h>.
Here's the prototype:

int stat (const char * file_name, struct stat * buf);

So from what I understand, it must pass a pointer to a stat structure so that it fills the structure correctly from file file_name.

I proceed like this:

 int FileExists (const char * sFileName) ( 
    struct stat * FileInformation = NULL; 
    printf ( "Error code:% d \ n", stat (sFileName, FileInformation)); 
    return 0; 
  )

I do not understand why it does not work ... I spend a good pointer to the function that I previously set to NULL ... Can any one give the example of Pointers to structures. Thank you all...

[Zecho]

But must be a pointer to point otherwise it is useless. In this case, it is necessary that you create the pointer variable and then the pointer to the variable and sending the pointer to the function.

[Walby]

Pointers to structures Example :

#include <iostream.h>
#include <stdlib.h>

struct student {
  char title [50];
  int year;
};


int main ()
{
  char buffer[50];

 student astudent;
  student * pstudent;
  pstudent = & astudent;

  cout << "Enter title: ";
  cin.getline (pstudent->title,50);
  cout << "Enter year: ";
  cin.getline (buffer,50);
  pstudent->year = atoi (buffer);

  cout << "\nYou have entered:\n";
  cout << pstudent->title;
  cout << " (" << pstudent->year << ")\n";

  return 0;

[Aberto]

#include <stdio.h>

typedef struct ro RO;

struct ro {
  char *address;
  int id;
  int no;
  float velocity;
};

void info(RO r);  /* declare functions */
void harm(RO *r);

int main() {
  RO r1 = {"Man Main", 140, 213, 5.1};
  RO r2 = {"Pla Pet", 170, 309, 4.5};

  RO *ptr_r1 = &r1;

  printf("Before damage: \n\n");

  info(r1);
  info(r2);

  harm(ptr_r1);
  harm(&r2);

  printf("\nAfter damage: \n\n");

  info(r1);
  info(r2);
  
  return 0;
}

void info(RO r) {
  printf("%s: id: %d   IQ: %d   ", r.address, r.id, r.no);
  printf("Velocity: %0.1f\n", r.velocity);
}

void harm(RO *r) {
  r->id -= 20;
  r->velocity -= 1;
}