我是 C 编程和 Ubuntu 的新手。我正在阅读 D.M Ritchie 的《C 编程语言》，其中我发现了以下代码：
#include <stdio.h>
int main()
{
int c;
int nc=0;
while((c = getchar()) != EOF)
{
nc++;
}
printf("%d Characters \n",nc);
return 0;
}
But while running the program I enter "Hello" ,then CTRL+D twice to get the actual number of characters which is 5.
But when I enter "Hello" then CTRL+D once, nothing happens, the terminal still waits for input.
Why?
Quoting @Veritas 的评论,
在 Linux 上，Ctrl-D 仅在缓冲区已为空时才起作用，否则它只会刷新缓冲区。因此，除非他之后按下 Enter 键时没有任何字符，否则他必须按 Ctrl-D 两次。
This explains the issue. You have to press it twice because you , after typing Hello, did not press the Enter to flush the input into the stdin. So the first time you press CTRL+D, it flushes the data into the stdin. The second time you press it, EOF is sent.
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