我目前正在尝试用这样的方式结束 while 循环:

#include <stdio.h>
int main() 
{
    while(getchar() != EOF)
    {
        if( getchar() == EOF )
            break;
    }
    return 0;

当我在我的 Ubuntu 上按下 CTRL+D 时，它会立即结束循环。但在 Windows 上我必须按 CTRL+Z 然后按 ENTER 关闭循环。我可以去掉 Windows 上的 ENTER 吗？

最佳答案

getchar 行为

对于 linux，EOF 字符是用 ctrl + d 写入的，而在 Windows 上，当您在之后按 enter 时，它是由控制台写入的通过 ctrl + z 更改 CRT 库的内部状态(保留此行为是为了与非常旧的系统兼容)。如果我没记错的话，它叫做文件的软结束。我不认为你可以绕过它，因为当你按下 enter 时，EOF char 实际上被你的 getchar 消耗了，而不是当你按下 ctrl + z.

据报道here :

In Microsoft's DOS and Windows (and in CP/M and many DEC operating systems), reading from the terminal will never produce an EOF. Instead, programs recognize that the source is a terminal (or other "character device") and interpret a given reserved character or sequence as an end-of-file indicator; most commonly this is an ASCII Control-Z, code 26. Some MS-DOS programs, including parts of the Microsoft MS-DOS shell (COMMAND.COM) and operating-system utility programs (such as EDLIN), treat a Control-Z in a text file as marking the end of meaningful data, and/or append a Control-Z to the end when writing a text file. This was done for two reasons:

• Backward compatibility with CP/M. The CP/M file system only recorded the lengths of files in multiples of 128-byte "records", so by convention a Control-Z character was used to mark the end of meaningful data if it ended in the middle of a record. The MS-DOS filesystem has always recorded the exact byte-length of files, so this was never necessary on MS-DOS.

• It allows programs to use the same code to read input from both a terminal and a text file.

还报告了其他信息here :

Some modern text file formats (e.g. CSV-1203[6]) still recommend a trailing EOF character to be appended as the last character in the file. However, typing Control+Z does not embed an EOF character into a file in either MS-DOS or Microsoft Windows, nor do the APIs of those systems use the character to denote the actual end of a file.

Some programming languages (e.g. Visual Basic) will not read past a "soft" EOF when using the built-in text file reading primitives (INPUT, LINE INPUT etc.), and alternate methods must be adopted, e.g. opening the file in binary mode or using the File System Object to progress beyond it.

Character 26 was used to mark "End of file" even if the ASCII calls it Substitute, and has other characters for this.

如果您这样修改代码:

#include <stdio.h>

int main() {
  while(1) {
    char c = getchar();
    printf("%d\n", c); 
    if (c == EOF)      // tried with also -1 and 26
      break;
  }
  return 0;
}

然后您对其进行测试，在 Windows 上您将看到 EOF (-1) 在您按下 enter 之前不会写入控制台。 Beore ^Z 是由终端仿真器打印的(我怀疑)。根据我的测试，如果出现以下情况，则会重复此行为:

• 您使用 Microsoft Compiler 进行编译
• 你使用 GCC 编译
• 你在CMD窗口运行编译好的代码
• 在 Windows 的 bash 模拟器中运行编译后的代码

使用 Windows 控制台 API 更新

按照@eryksun 的建议，我成功地为 Windows 编写了一个(对于它的功能来说复杂得离谱)代码，它改变了 conhost 的行为以实际获得“按 ctrl + < 时退出”="" kbd="">d”。它并不能处理所有事情，它只是一个例子。 恕我直言，这是要尽可能避免的事情，因为可移植性小于 0。此外，要实际正确处理其他输入情况，应该编写更多代码，因为这东西会从控制台分离标准输入，你必须自己处理它。

这些方法或多或少地工作如下:

• 获取标准输入的当前处理程序
• 创建一个输入记录数组，该结构包含有关在主机窗口中发生的事情(键盘、鼠标、调整大小等)的信息
• 读取窗口中发生的事情(它可以处理事件的数量)
• 遍历事件 vector 以处理键盘事件并拦截所需的 EOF(根据我的测试，这是一个 4)用于退出，或打印任何其他 ascii 字符。

这是代码:

#include <windows.h>
#include <stdio.h>

#define Kev input_buffer[i].Event.KeyEvent // a shortcut

int main(void) {
  HANDLE h_std_in;                // Handler for the stdin
  DWORD read_count,               // number of events intercepted by ReadConsoleInput
        i;                        // iterator
  INPUT_RECORD input_buffer[128]; // Vector of events

  h_std_in = GetStdHandle( // Get the stdin handler
    STD_INPUT_HANDLE       // enumerator for stdin. Others exist for stdout and stderr
  ); 

  while(1) {
    ReadConsoleInput( // Read the input from the handler
      h_std_in,       // our handler 
      input_buffer,   // the vector in which events will be saved
      128,            // the dimension of the vector
      &read_count);   // the number of events captured and saved (always < 128 in this case)

    for (i = 0; i < read_count; i++) {    // and here we iterate from 0 to read_count
      switch(input_buffer[i].EventType) { // let's check the type of event 
        case KEY_EVENT:                   // to intercept the keyboard ones
          if (Kev.bKeyDown) {             // and refine only on key pressed (avoid a second event for key released)
            // Intercepts CTRL + D
            if (Kev.uChar.AsciiChar != 4)
              printf("%c", Kev.uChar.AsciiChar);
            else
              return 0;
          }
          break;
        default:
          break;
      }
    }
  }

  return 0;
}

关于c - 使用 EOF 结束循环(不输入)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46950315/