How to copy a heap object to preserve it from destroying? - c

Question

I have an object allocated on the heap. The object will be destroyed from the heap, but I need to preserve it, preferably through copying it and saving the pointer to it.
An example
#include <stdio.h>
#include <stdlib.h>
struct Human
{
int age;
char sex;
float height;
float weight;
};
struct Human *human;
void create_human(int age, char sex, float height, float weight)
{
struct Human *A = (struct Human *) malloc(sizeof(struct Human));
A->age = age;
A->sex = sex;
A->height = height;
A->weight = weight;
// copy A and save the pointer to the copy in the global variable
free(A);
}
int main()
{
create_human(22, 'M', 1.90, 100.0);
printf("Age: %d\tSex: %c\tHeight %.2f\tWeight %.2f\n", human->age, human->sex, human->height, human->weight);
}
Here I need to copy the object A points to and make human point to the copy.

Answer 1

human = (struct Human *) malloc(sizeof(struct Human));
memcpy(human, A, sizeof(struct Human));
If there were pointers to other structs inside Human, this would be slightly more complex!
Edit:
More elegant solution suggested by StoryTeller in comments:
human = (struct Human *) malloc(sizeof(struct Human));
*human = *A;

Answer 2

You probably want something like this:
no more obscure copying into a global variable (avoid global variables whenever possible)
no more cast for malloc
free called once we're done with the created human and not before
#include <stdio.h>
#include <stdlib.h>
struct Human
{
int age;
char sex;
float height;
float weight;
};
struct Human *create_human(int age, char sex, float height, float weight)
{
struct Human *A = malloc(sizeof(struct Human)); // no need to cast
A->age = age;
A->sex = sex;
A->height = height;
A->weight = weight;
return A;
}
int main()
{
struct Human *human = create_human(22, 'M', 1.90, 100.0);
printf("Age: %d\tSex: %c\tHeight %.2f\tWeight %.2f\n", human->age, human->sex, human->height, human->weight);
free(human);
}
If you absolutely want to copy your human into a global variable, you can still do it:
...
struct human *globalhuman;
...
int main()
{
globalhuman = create_human(22, 'M', 1.90, 100.0);
printf("Age: %d\tSex: %c\tHeight %.2f\tWeight %.2f\n", globalhuman ->age, globalhuman ->sex, globalhuman ->height, globalhuman ->weight);
free(globalhuman );
}