#include <stdio.h>
#define  KMS_PER_MILES  1.609
#include<conio.h>
  
int
main()
{
          double  miles, kms;
          FILE    *inp,
                  *outp;
         
          inp = fopen ("b:distance.txt" , "r");
          outp = fopen ("b:disout.txt" , "w");
         
          fscanf(inp, "%lf",&miles);
          fprintf(outp,"The distance in miles is %.2f.\n",miles);
         
          kms = KMS_PER_MILES * miles;
          fprintf(outp , "That equals %.2f kilometers.\n",kms);
         
          fclose(inp);
          fclose(outp);
         
          getch();
          getch();
          return (0);
          }
         
 这个程序那里错啦？为什么运行结果什么也没有？谢谢各位高手的指教。         

文件格式不对。

楼上正解

oh  !  理解!