Explorations in C

persons.c

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

// A simple struct, we'll use "PersonStruct"
// for clarity
struct PersonStruct 
{
	char *name;
	int age;
	int height;
	int weight;
};


// By defining a "Person" type,
// we can pass the value back and forth
// without using a pointer (and thus we
// doint have to worry about the stack
// clearing the value)
//
// UPDATE: We can DRY this out by passing the struct
//         instead of redefining properties
typedef struct PersonStruct Person;


// We can use this function to create a person
// and return it.
Person createPersonStack()
{
	Person guy; // Notice we don't need to use a pointer
	
	guy.name = "Nate";
	guy.age = 23;
	guy.height = 72;
	guy.weight = 155;
		
	return guy;
}


struct PersonStruct *createPersonHeap()
{
	// Create a Person using our struct with a pointer
	// Note that we use malloc so that the pointer
	// isn't cleared from the stack when this function
	// ends (causing a segfault when accessing a property of
	// the returned Person, "guy"
	struct PersonStruct *guy = malloc(sizeof(struct PersonStruct));
	assert(guy != NULL); // Let's make sure we have enough memory!
	
	// Message notation...
	guy->name = "Nate";
	guy->age = 23;
	
	// Dot donation...
	(*guy).height = 72;
	(*guy).weight = 155;
	
	return guy;
}

int main(int argc, char *argv[]) 
{
	Person me = createPersonStack();
	printf("Stack Person: %s\n", me.name);
	
	struct PersonStruct *otherMe = createPersonHeap();
	printf(" Heap Person: %s\n", otherMe->name);
	
	free(otherMe);
}