c - I get an error with fopen -

when go , compile lab, 1 error. if tell me doing wrong awesome, because right stuck. error seems fopen statement, our teacher hasn't taught really, told use it. lot in advance

lab1.c: in function ‘read_file’: lab1.c:65: warning: passing argument 1 of ‘fopen’ incompatible pointer type /usr/include/stdio.h:271: note: expected ‘const char * __restrict__’ argument of  type 'struct file *' 

here code:

//libraries #include<stdio.h> #include<stdlib.h> #include<string.h>  #define max_name_length 20 #define max_array_length 25  //structure typedef struct student_{     char name[max_name_length];     int num_a;     int num_b;     int num_c;     int num_d;     int num_f;     float gpa; }student;  student class[max_array_length];  //prototypes int read_file(file *input); void print_grade_distribution(int num_students); void calculate_gpa(int *index); void write_to_file(file *output, int num_students);  int main(int argc, char* argv[]){      if(argc != 2)     {             printf("insufficient arguments");             exit(exit_failure);     }      if(argv[1] == null)     {             printf("failed print.");             exit(exit_failure);     }      file *infile;     file *outfile;     int num_students = read_file(infile); print_grade_distribution(num_students);      write_to_file(outfile, num_students);   }   int read_file(file* input){      int i;     file *infile;     input = fopen(infile, "r");      if(input == null)     {             printf("file failed open.");             exit(exit_failure);     }      int num_students;     fscanf(input, "%d", &num_students);      for(i = 0; < num_students; i++){             fscanf(input, "%c %d %d %d %d", &class[i].name, &class[i].num_a, &class[i].num_b, &class[i].num_c, &class[i].num_d, &class[i].num_f);     }      int *index;     calculate_gpa(index);      fclose(input);     return num_students; }  void print_grade_distribution(int num_students){      int i;     int j;      printf("\na:");     (i = 0; < num_students; i++){             for(j = 0; j < class[i].num_a; j++){                     printf("-");     }}      printf("\nb:");     for(i = 0; < num_students; i++){             for(j = 0; j < class[i].num_b; j++){                     printf("-"); printf("\nc:");     for(i = 0; < num_students; i++){             for(j = 0; j < class[i].num_c; j++){                     printf("-");     }}      printf("\nd:");     for(i = 0; < num_students; i++){             for(j = 0; j < class[i].num_d; j++){                     printf("-");     }}      printf("\nf:");     for(i = 0; < num_students; i++){             for(j = 0; j < class[i].num_f; j++){                     printf("-");     }} }  void calculate_gpa(int *index){      int i;     int gpa;     int as, bs, cs, ds, fs;     int index1 = *index;     for(i = 0; < index1; i++){              if (class[i].num_a != 0){                     gpa = class[i].num_a * 4;                     = class[i].num_a;             }             if (class[i].num_b != 0){                     gpa = gpa + (class[i].num_b *3);                     bs = class[i].num_b;             }             if (class[i].num_c != 0){                     gpa = gpa + (class[i].num_c *2);                     cs = class[i].num_c;             }             if (class[i].num_d != 0){                     gpa = gpa + (class[i].num_d *1);                     ds = class[i].num_d;             }             if (class[i].num_f != 0){                     gpa = gpa + (class[i].num_f * 0);                     fs = class[i].num_f;             }      gpa = gpa / (as + bs + cs + ds + fs);      gpa = class[i].gpa; }   }   void write_to_file(file *output, int num_students){      int i;     for( = 0; <= num_students; i++)             fprintf(output, "%c %d\n", &class[i].name, &class[i].gpa);     fclose(output); } 

infile should char* containing string file location. not file*.

see documentation fopen.