c - 获取无限循环的问号

Question

这个问题已经有答案了:

Why is “while( !feof(file) )” always wrong? (5 个回答)

已关闭 7 年前。

我正在尝试运行 Deitel 教科书“C 如何编程”中的这个简单程序，该程序扫描来自 stdin 的输入并将它们放入文件中。

#include <stdio.h>

int main( void )
{ 
   int account; /* account number */
   char name[ 30 ]; /* account name */
   double balance; /* account balance */

   FILE *cfPtr; /* cfPtr = clients.dat file pointer */

   /* fopen opens file. Exit program if unable to create file  */
   if ( ( cfPtr = fopen( "clients.dat", "w" ) ) == NULL ) {
      printf( "File could not be opened\n" );
   } /* end if */
   else { 
      printf( "Enter the account, name, and balance.\n" );
      printf( "Enter EOF to end input.\n" );
      printf( "? " );
      scanf( "%d%s%lf", &account, name, &balance );

      /* write account, name and balance into file with fprintf */
      while ( !feof( stdin ) ) { 
         fprintf( cfPtr, "%d %s %.2f\n", account, name, balance );
         printf( "? " );
         scanf( "%d%s%lf", &account, name, &balance );
      } /* end while */

      fclose( cfPtr ); /* fclose closes file */
   } /* end else */

   return 0; /* indicates successful termination */
} /* end main */

当我输入此内容时

Enter the account, name, and balance. Enter EOF to end input.
? 100 Jones 24.98
? 200 Doe 345.67
? 300 White 0.00
? 400 Stone -42.16 
? 500 Rich 224.62 
? EOF
????????????????????..........(cont.)

后面是无限循环的“？”。 client.dat 文件已损坏并带有“？”人物。这里有什么问题吗？

编辑

看起来 MacOSX 上的 Ctrl+D 就可以了。

Answer 1

请尝试一下，运行良好。您的代码几乎很好，只是循环中有一点困惑。我修改了 STRICT MINIMUM 以使其运行，并给您留下了一些工作要做。将 EOF 替换为 0 ，看起来更简单，但这取决于你。

#include

int main( void )
{
  int account;          /* account number */
  char name[30];        /* account name */
  double balance;       /* account balance */

  FILE *cfPtr;          /* cfPtr = clients.dat file pointer */

  /* fopen opens file. Exit program if unable to create file  */
  if ( ( cfPtr = fopen( "clients.dat", "w" ) ) == NULL )
  {
    printf( "File could not be opened\n" );
    return ( 0 );
  }             /* end if */
  // else {

  while ( 1 )
  {
    printf( "Enter the account, name, and balance.\n" );
    printf( "Enter 0 to end input.\n" );
    printf( "? " );
    scanf( "%d%s%lf", &account, name, &balance );
    if ( account == 0 )
      break;
    /* write account, name and balance into file with fprintf */
    //while ( !feof( stdin ) ) {
    fprintf( cfPtr, "%d %s %.2f\n", account, name, balance );
    //printf( "? " );
    // scanf( "%d%s%lf", &account, name, &balance );
  }             /* end while */

  fclose( cfPtr );      /* fclose closes file */
}               /* end else */