Sorting a list of students by name and grade using struct in C -

i'm writing program sorts list of students name , grade. i'm receiving following errors when attempt compile:

 ex11.c: in function 'comparebygrade': ex11.c:46: error: request member 'grade' in not structure or union ex11.c:47: error: request member 'grade' in not structure or union ex11.c: in function 'comparebyname': ex11.c:56: error: request member 'name' in not structure or union ex11.c:57: error: request member 'name' in not structure or union 

this header file:

#define class_size 10  struct student {     char *name;     int  idnumber;     char grade; }; 

this main file:

#include <stdio.h> #include <stdlib.h> #include <string.h> #include "ex11.h"  int main(void) {     int c, i;     file *data;     struct student tmp, class[class_size];     void *namearray[class_size], *gradearray[class_size];     static int comparebygrade(const void *first, const void *second);     static int comparebyname(const void *first, const void *second);      data = fopen("data", "r");                         /* open data file */  /* move data struct */      (i = 0; < class_size; ++i) {             fscanf(data, "%s%d%c", tmp.name, tmp.idnumber, tmp.grade);             class[i].name = tmp.name;             class[i].idnumber = tmp.idnumber;             class[i].grade = tmp.grade;     }     fclose(data);                                     /* close data file */     qsort(namearray, class_size, sizeof(*namearray), &comparebyname);     qsort(gradearray, class_size, sizeof(*gradearray), &comparebygrade); }  /* function sorty grade */  static int comparebygrade(const void *first, const void *second) {     const char *firstgrade = (*(const char **) first) -> grade; /* line 46 */     const char *secondgrade = (*(const char **) second) -> grade; /* line 47 */      return strcmp(firstgrade, secondgrade); }  /* function sort name */  static int comparebyname(const void *first, const void *second) {     const char *firstname = (*(const char **) first) -> name; /* line 56 */     const char *secondname = (*(const char **) second) -> name; /* line 57 */      return strcmp(firstname, secondname); } 

what doing wrong?

agreed xaxxon. program processes struct student class, namearray , gradearray never initialized.

btw,i suppose not use struct named class, it's confused c++'s keyword.

grade char, strcmp() need string compare.

suggestion: in main(),

qsort(class, class_size, sizeof(struct student*), &comparebyname); qsort(class, class_size, sizeof(struct student*), &comparebygrade); 

and outside,

int comparebygrade(const void *first, const void *second) {     const char firstgrade = ((struct student *)first) -> grade;     const char secondgrade = ((struct student *)second) -> grade;     return firstgrade<secondgrade?-1:(firstgrade==secondgrade?0:1); }  /* function sort name */  int comparebyname(const void *first, const void *second) {     const char *firstname = ((struct student *)first) -> name;     const char *secondname = ((struct student *)second) -> name;      return strcmp(firstname, secondname); } 

the expression of return value of comparebygrade() act in same way of comparebyname()