c - How to access a structures' members outside of its original function? -

i working on project creating structures inside of separate function main(). after being created , added member (variable) information structure variable, need able return pointer structure in can access reference , printing.

i including code , please simple possible new structures.

#include <stdio.h> #include <stdlib.h> #include<string.h>  typedef struct _car {     char color[20];     char model[20];     char brand[20];     int year;     struct _car *eptr; } car;  car* readcars(char* filename);   /*  *   */ int main(int argc, char** argv) {     car *cars;     car *eptr;      cars = readcars(argv[1]);      printf("%s%s%s%s", cars->color, cars->brand, cars->model, cars->color);      return (exit_success); }  car* readcars(char* filename) {     file *file = fopen(filename, "r");     int year;     char color [20], model [20], brandx[20];     car car1;     car car2;     car *carptr;     car *car2ptr;     if (file == null)     {         printf("file cannot opened\n");     }     while(file != eof)     {          fscanf(file, "%s%s%s%d", color, model, brandx, &year);          strcpy(car1.color, color);         strcpy(car1.model, model);         strcpy(car1.brand, brandx);         car1.year = year;          carptr = &car1;         fscanf(file, "%s%s%s%d", color, model, brandx, &year);          strcpy(car2.color, color);         strcpy(car2.model, model);         strcpy(car2.brand, brandx);         car2.year = year;         car2ptr = &car2;          if (fscanf(file, "%s%s%s%d", color, model, brandx, &year) == eof)         {             break;         }     }      return carptr;         } 

to answer main question in post, in car* readcars(char* filename) function, you're storing address of local variable pointer

carptr = &car1; 

and trying return it

return carptr; 

in case, readcars() function finisihes execution, existence of car ceased , you'll invoking undefined behaviour accessing returned pointer.

if want memory valid outside scope of it's allocation (in case, outside readcars() function), need allocate same using dynamic memory allocation, example, malloc() , family.

fwiw, once you've done using returned pointer, need free() memory avoid memory leak.

---

that said,

1. you never effectively checked success of fopen() or of fscanf(). if either of them failed, continuing normally ideal scenario invoking ub.
2. while ( !feof (fp) ) bad
3. pointer arithmetic(s) in code is(are) meaningless.
4. you've got syntax errors...and maybe more.