#include <stdio.h>

struct student_data {
    int  student_id;
    unsigned char marks[10];
};

void main()
  {
    FILE *fp;
    struct student_data std;
    int i;

    fp = fopen( "file", "w" );
    if( fp != NULL ) {
      std.student_id = 1001;
      for( i = 0; i < 10; i++ )
        std.marks[ i ] = (unsigned char) (85 + i);

      /* write student record with marks */
      i = fwrite( &std, sizeof(std), 1, fp );
      printf( "%d record written\n", i );
      fclose( fp );
    }
  }