struct - Learn C the hard way excercise 16 -

i inexperienced programmer working through learn c hard way , stuck on credit exercise.

http://c.learncodethehardway.org/book/ex16.html

i trying adapt code , making struct on stack instead of heap code giving me segmentation fault , unsure why or how proceed. advice appreciated.

#include <stdio.h> #include <stdlib.h> #include <string.h>  struct person {     char *name;     int age;     int height;     int weight; };  void person_create(struct person p,char *name,int age,int height,int weight) {     p.name = name;     p.age = age;     p.height = height;     p.weight = weight; }  void person_print(struct person who) {     printf("name: %s\n", who.name);     printf("\tage: %d\n", who.age);     printf("\theight: %d\n", who.height);     printf("\tweight: %d\n", who.weight); }  int main(int argc, char *argv[]) {     // make 2 people structures     struct person joe;     struct person frank;     person_create(             joe,"joe alex",32,64,140);      person_create(             frank,"frank blank",20,72,180);      // print them out     person_print(joe);     person_print(frank); ;      // make age 20 years , print them again     joe.age += 20;     joe.height -= 2;     joe.weight += 40;     person_print(joe);      frank.age += 20;     frank.weight += 20;     person_print(frank);      return 0; } 

the reason code produces errors @ runtime c passes structs value, meaning following assignments inside person_create have no effect:

p.name = name; p.age = age; p.height = height; p.weight = weight; 

this makes no changes joe , frank inside main(), leading undefined behavior on printing, because name data member of struct person remains uninitialized.

in order fix problem, pass struct person pointer, , apply -> operator in place of . operator:

void person_create(struct person *p,char *name,int age,int height,int weight) {     p->name = name;     p->age = age;     p->height = height;     p->weight = weight; } ... person_create(&joe, "joe alex", 32, 64, 140); //            ^ pass address 

it asking me not use pointers or malloc, , says advice creating struct on stack

your code creates structs on stack. if rid of pointers completely, change person_create *return` new person, this:

struct person person_create(char *name,int age,int height,int weight) {     struct person p;     p.name = name;     p.age = age;     p.height = height;     p.weight = weight;     return p; } ... joe = person_create("joe alex", 32, 64, 140);