C - Returning a pointer to a structure from a function

Description

Returning a pointer to a structure from a function
Demo

#define __STDC_WANT_LIB_EXT1__ 1
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdbool.h>

typedef struct Date Date;
typedef struct Family Family;

// Function prototypes
Family *get_person(void);                                        // Input function
void show_people(bool forwards, Family *pfirst, Family *plast);  // Output function
void release_memory(Family *pfirst);                             // Release heap memory

struct Date//  w w  w  . ja va2 s.  co  m
{
  int day;
  int month;
  int year;
};

struct Family                          // Family structure declaration
{
  Date dob;
  char name[20];
  char father[20];
  char mother[20];
  Family *next;                        // Pointer to next structure
  Family *previous;                    // Pointer to previous structure
};

int main(void)
{
  Family *first = NULL;                // Pointer to first person
  Family *current = NULL;              // Pointer to current person
  Family *last = NULL;                 // Pointer to previous person
  char more = '\0';                    // Test value for ending input

  while (true)
  {
    printf_s("\nDo you want to enter details of a%s person (Y or N)? ",
      first != NULL ? "nother" : "");
    scanf_s(" %c", &more, sizeof(more));
    if (tolower(more) == 'n')
      break;

    current = get_person();

    if (first == NULL)
      first = current;                 // Set pointer to first Family
    else
    {
      last->next = current;            // Set next address for previous Family
      current->previous = last;        // Set previous address for current
    }
    last = current;                    // Remember for next iteration
  }

  show_people(true, first, last);      // Tell them what we know
  release_memory(first);
  first = last = NULL;
  return 0;
}
Family *get_person(void)
{
  Family *temp = (Family*)malloc(sizeof(Family));

  printf_s("\nEnter the name of the person: ");
  scanf_s("%s", temp->name, sizeof(temp->name));

  printf_s("\nEnter %s's date of birth (day month year); ", temp->name);
  scanf_s("%d %d %d", &temp->dob.day, &temp->dob.month, &temp->dob.year);

  printf_s("\nWho is %s's father? ", temp->name);
  scanf_s("%s", temp->father, sizeof(temp->father));

  printf_s("\nWho is %s's mother? ", temp->name);
  scanf_s("%s", temp->mother, sizeof(temp->mother));

  temp->next = temp->previous = NULL;    // Set pointer members to NULL

  return temp;                           // Return address of Family structure
}

void show_people(bool forwards, Family *pfirst, Family *plast)
{
  printf_s("\n");
  for (Family *pcurrent = forwards ? pfirst : plast;
    pcurrent != NULL;
    pcurrent = forwards ? pcurrent->next : pcurrent->previous)
  {
    printf_s("%s was born %d/%d/%d and has %s and %s as parents.\n",
      pcurrent->name, pcurrent->dob.day, pcurrent->dob.month,
      pcurrent->dob.year, pcurrent->father, pcurrent->mother);
  }
}


void release_memory(Family *pfirst)
{
  Family *pcurrent = pfirst;
  Family *temp = NULL;
  while (pcurrent)
  {
    temp = pcurrent;
    pcurrent = pcurrent->next;
    free(temp);
  }
}
C - Returning a pointer to a structure from a function

Description

Demo

Result

Related Topic
