typedef - Defining variable for recursive data structure in C -

i have function sortbyname returns recursive data structure sortedlist. sortlist contains pointer recursive data structure stud_type , defined below.

typedef struct stud_type_ {     int    matricnum;                      char   name[20];                struct stud_type_ *next_student; } stud_type;  typedef struct sort_list {     stud_type *cur;     struct sortlist *next; } sortlist;  stud_type listofstudents; // assume not null  sortlist * sortbyname() {     sortlist *slist;      //sort algorithm here     return slist; } ... ...  int main() { //trying define curtest = sortbyname() here     while (curtest!=null) {         printf("name: %s\n", curtest->cur->name);         curtest = curtest->next;     } } 

now assign variable in main() function hold return value sortbyname function can iterate through while loop , print out results. how define variable? tried sortlist curtest; , sortlist * curtest; no avail. or there wrong definition of sortbyname function?

edit: i've tried compiling , corrected of trivial , not trivial errors/warnings until came current error report doesn't make sense me.

u2_4.c:208:15: warning: implicit declaration of function 'sortbyname' invalid in c99       [-wimplicit-function-declaration]     curtest = sortbyname();                ^ u2_4.c:208:13: warning: incompatible integer pointer conversion assigning 'sortlist *'     (aka 'struct sort_list *') 'int' [-wint-conversion]     curtest = sortbyname();              ^ ~~~~~~~~~~~~~~~~~~ 2 warnings generated. undefined symbols architecture x86_64:   "_sortbyname", referenced from:       _main in u2_4-szd3la.o ld: symbol(s) not found architecture x86_64 clang: error: linker command failed exit code 1 (use -v see invocation) make: *** [u2_4] error 1 

in main function, defined curtest this: sortlist * curtest;

are defining function in different file... or after define main()? if defined elsewhere , not have function prototype before main(), warnings , linker error.

i did following in single file (main.c) , compiled without issues.

typedef struct stud_type_ {     int    matricnum;     char   name[20];      struct stud_type_ *next_student; } stud_type;  typedef struct sort_list {     stud_type *cur;     struct sort_list *next; } sortlist;  stud_type listofstudents; // assume not null  sortlist * sortbyname() {     sortlist *slist;      //sort algorithm here     return slist; }  int main() {     sortlist * curtest = sortbyname();      while (curtest!=null) {         printf("name: %s\n", curtest->cur->name);         curtest = curtest->next;     }     return 0; } 

note made 2 changes file. changed structure sortlist when defining pointer next. changed struct sortlist *next struct sort_list *next. , defined , initialized curtest sortlist * curtest = sortbyname().