Lab 5 - Inheritance check50 error

Question

Attempted CS50 Lab 5 inheritance. My code looks correct and compiles. I also double-checked with Brian's solution and they were identical. Yet when I passed it through check50, I got multiple errors as shown:

Can somebody help me with this? Thank you!

The code is as follows:

// Simulate genetic inheritance of blood type

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

// Each person has two parents and two alleles
typedef struct person
{
    struct person *parents[2];
    char alleles[2];
} person;

const int GENERATIONS = 3;
const int INDENT_LENGTH = 4;

person *create_family(int generations);
void print_family(person *p, int generation);
void free_family(person *p);
char random_allele();

int main(void)
{
    // Seed random number generator
    srand(time(0));

    // Create a new family with three generations
    person *p = create_family(GENERATIONS);

    // Print family tree of blood types
    print_family(p, 0);

    // Free memory
    free_family(p);
    return 0;
}

// Create a new individual with `generations`
person *create_family(int generations)
{
    // TODO: Allocate memory for new person
    person *p = malloc(sizeof(person));

    // If there are still generations left to create
    if (generations > 1)
    {
        // Create two new parents for current person by recursively calling create_family
        person *parent0 = create_family(generations - 1);
        person *parent1 = create_family(generations - 1);

        // TODO: Set parent pointers for current person
        p->parents[0] = parent0;
        p->parents[1] = parent1;
        // TODO: Randomly assign current person's alleles based on the alleles of their parents
        int r = rand() % 2;
        p->alleles[0] = p->parents[0]->alleles[r];
        p->alleles[1] = p->parents[1]->alleles[r];
    }

    // If there are no generations left to create
    else
    {
        // TODO: Set parent pointers to NULL
        p->parents[0] = NULL;
        p->parents[1] = NULL;
        // TODO: Randomly assign alleles
        p->alleles[0] = random_allele();
        p->alleles[1] = random_allele();
    }

    // TODO: Return newly created person
    return p;
}

// Free `p` and all ancestors of `p`.
void free_family(person *p)
{
    // TODO: Handle base case
    if (p == NULL)
    {
        return;
    }
    // TODO: Free parents recursively
    free_family(p ->parents[0]);
    free_family(p ->parents[1]);
    // TODO: Free child
    free_family(p);
}

// Print each family member and their alleles.
void print_family(person *p, int generation)
{
    // Handle base case
    if (p == NULL)
    {
        return;
    }

    // Print indentation
    for (int i = 0; i < generation * INDENT_LENGTH; i++)
    {
        printf(" ");
    }

    // Print person
    if (generation == 0)
    {
        printf("Child (Generation %i): blood type %c%c\n", generation, p->alleles[0], p->alleles[1]);
    }
    else if (generation == 1)
    {
        printf("Parent (Generation %i): blood type %c%c\n", generation, p->alleles[0], p->alleles[1]);
    }
    else
    {
        for (int i = 0; i < generation - 2; i++)
        {
            printf("Great-");
        }
        printf("Grandparent (Generation %i): blood type %c%c\n", generation, p->alleles[0], p->alleles[1]);
    }

    // Print parents of current generation
    print_family(p->parents[0], generation + 1);
    print_family(p->parents[1], generation + 1);
}

// Randomly chooses a blood type allele.
char random_allele()
{
    int r = rand() % 3;
    if (r == 0)
    {
        return 'A';
    }
    else if (r == 1)
    {
        return 'B';
    }
    else
    {
        return 'O';
    }
}

Answer 1

Your free_family function doesnt actually free anything, it just recursively calls itself in a manner it should... until it gets to a leaf node and calls itself infinitely. I think instead of free_family(p) you want free(p) at the end of the function

This should prevent you from ever terminating unless the compiler optimizes it away and would cause you to fail. despite appearing to otherwise print out reasonable output.

Answer 2

1.You need to change free_family into free function. 2.int r = rand() % 2; p->alleles[0] = p->parents[0]->alleles[r]; p->alleles[1] = p->parents[1]->alleles[r];

You need to change parents[0] &parents[1] into parent0 & parent1,as it is defined before.