#include <stdio.h>

int fr ( void );

int main ( void )
{
  int ret;

  ret = fr ( );

  //...

  return ( 0 );
}

int fr ( void )
{
  FILE *stream = NULL;
  char  s[ 100 ];
  int   n;

  if ( NULL == ( stream = fopen ( "data", "r" ) ) )
  {
    printf ( "The file 'data' was not opened\n" );
    return ( -1 );
  }
  else
  {
    printf ( "The file 'data' was opened\n" );
    n = fscanf ( stream, "%s", s );

    //...

    fclose ( stream );  //遵循1

    return ( 0 );
  }
}